SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D

                   Under the Securities Exchange Act of 1934*

                             Unisource Energy Corp.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                           Common Stock, no par value
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    909205106
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                      (CUSIP Number of Class of Securities)

                                 Daniel S. Loeb
                      Third Point Management Company L.L.C.
                         360 Madison Avenue, 24th Floor
                               New York, NY 10017
                                 (212) 224-7400
--------------------------------------------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                   Copies to:
                            Daniel Schloendorn, Esq.
                          Willkie Farr & Gallagher LLP
                               787 Seventh Avenue
                             New York, NY 10019-6099
                                 (212) 728-8000

                                January 26, 2005
--------------------------------------------------------------------------------
                          (Date of Event which Requires
                            Filing of this Schedule)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of ss.ss. 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box: [ ]

NOTE: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 240.13d-7 for other
parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).




                                  SCHEDULE 13D

-------------------                                           ------------------
CUSIP No. 909205106                                           Page 2 of 11 Pages
-------------------                                           ------------------

----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Daniel S. Loeb
----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP             (a) [ ]
                                                                         (b) [X]

----------- --------------------------------------------------------------------
    3       SEC USE ONLY

----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT
            TO ITEMS 2(d) or 2(e)                                            [ ]

----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
NUMBER OF                8      SHARED VOTING POWER
SHARES
BENEFICIALLY                    2,900,000
OWNED BY              --------- ------------------------------------------------
EACH                     9      SOLE DISPOSITIVE POWER
REPORTING
PERSON WITH                     0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                2,900,000
----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            2,900,000
----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*                                                          [ ]

----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            8.5%
----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            IN
----------- --------------------------------------------------------------------




                                  SCHEDULE 13D

-------------------                                           ------------------
CUSIP No. 909205106                                           Page 3 of 11 Pages
-------------------                                           ------------------

----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Third Point Management Company L.L.C.               I.D. #13-3922602
----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP             (a) [ ]
                                                                         (b) [X]

----------- --------------------------------------------------------------------
    3       SEC USE ONLY

----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT
            TO ITEMS 2(d) or 2(e)                                            [ ]

----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware
--------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
NUMBER OF                8      SHARED VOTING POWER
SHARES
BENEFICIALLY                    2,900,000
OWNED BY              --------- ------------------------------------------------
EACH                     9      SOLE DISPOSITIVE POWER
REPORTING
PERSON WITH                     0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                2,900,000
----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            2,900,000
----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*                                                          [ ]

----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            8.5%
----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            OO
----------- --------------------------------------------------------------------




                                  SCHEDULE 13D

-------------------                                           ------------------
CUSIP No. 909205106                                           Page 4 of 11 Pages
-------------------                                           ------------------

----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Third Point Offshore Fund Ltd.
----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP             (a) [ ]
                                                                         (b) [X]

----------- --------------------------------------------------------------------
    3       SEC USE ONLY

----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT
            TO ITEMS 2(d) or 2(e)                                            [ ]

----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands
--------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
NUMBER OF                8      SHARED VOTING POWER
SHARES
BENEFICIALLY                    1,714,700
OWNED BY              --------- ------------------------------------------------
EACH                     9      SOLE DISPOSITIVE POWER
REPORTING
PERSON WITH                     0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                1,714,700
----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            1,714,700
----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES*                                                          [ ]

----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            5.0%
----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            OO
----------- --------------------------------------------------------------------




     This Schedule 13D is being filed on behalf of Third Point Management
Company L.L.C., a Delaware limited liability company (the "Management Company"),
Third Point Offshore Fund, Ltd., a Cayman Islands limited liability exempted
company (the "Offshore Fund"), and Daniel S. Loeb, an individual ("Mr. Loeb",
together with the Offshore Fund and the Management Company, the "Reporting
Persons"). This Schedule 13D relates to the Common Stock, no par value, of
Unisource Energy Corp., an Arizona corporation (the "Company"). Unless the
context otherwise requires, references herein to the "Common Stock" are to such
Common Stock. This Schedule 13D is being filed to report that the beneficial
ownership of the Reporting Persons is in excess of 5% of the total outstanding
Common Stock. The Management Company is the investment manager or adviser to a
variety of hedge funds and managed accounts (such funds and accounts,
collectively, including, but not limited to the Offshore Fund, the "Funds"). Mr.
Loeb is the managing member of the Management Company. The Funds directly own
the Common Stock to which this Schedule 13D relates, and the Reporting Persons
may be deemed to have beneficial ownership over such Common Stock, by virtue of
the authority granted to the Management Company by the Funds to vote and to
dispose of the securities held by the Funds.

Item 1.   Security and Issuer.

     This statement on Schedule 13D relates to the Common Stock of the Company,
and is being filed pursuant to Rules 13d-1 and 13d-5 under the Securities
Exchange Act of 1934, as amended (the "Exchange Act"). The address of the
principal executive offices of the Company is One South Church Avenue, Suite 100
Tucson, AZ 85701.

Item 2.   Identity and Background.

     (a) This statement is filed by the Reporting Persons. Daniel S. Loeb is the
managing member of the Management Company and controls the Management Company's
business activities. The Management Company is organized as a limited liability
company under the laws of the State of Delaware. The Offshore Fund is organized
as a limited liability exempted company under the laws of the Cayman Islands.

     (b) The address of the principal business and principal office of the
Management Company and Mr. Loeb is 360 Madison Avenue, 24th Floor, New York, NY
10017. The address of the principal business and principal office of the
Offshore Fund is c/o Walkers SPV Limited, Walker House, Mary Street, P.O. Box
908GT, George Town, Grand Cayman, Cayman Islands, British West Indies.

     (c) The principal business of the Management Company is to serve as
investment manager or adviser to the Funds. The principal business of Mr. Loeb
is to act as the managing member of


                                       5




the Management Company. The principal business of the Offshore Fund is to invest
and trade in securities.

     (d) None of the Reporting Persons, nor, to the best of their knowledge, any
of their directors, executive officers, general partners or members has, during
the last five years, been convicted in a criminal proceeding (excluding traffic
violations or similar misdemeanors).

     (e) None of the Reporting Persons, nor, to the best of their knowledge, any
of their directors, executive officers, general partners or members has, during
the last five years, been a party to a civil proceeding of a judicial or
administrative body of competent jurisdiction and as a result of such proceeding
was or is subject to a judgment, decree or final order enjoining future
violations of, or prohibiting or mandating activities subject to, federal or
state securities laws or finding any violation with respect to such laws.

     (f) Mr. Loeb is a United States citizen.

Item 3.   Source and Amount of Funds or Other Consideration.

     The Funds expended an aggregate of $85,109,714.95 of their own investment
capital to acquire the 2,900,000 shares of Common Stock currently held by them
(the "Shares"). The Offshore Fund expended an aggregate of $50,314,381.70 of its
own investment capital to acquire the 1,714,700 Shares. In the case of the
Funds, the Shares were acquired through open market purchases.

                  The Funds effect purchases of securities primarily through
     margin accounts maintained for them with Bear, Stearns Securities Corp. and
Goldman, Sachs & Co. (the "Primary Brokers") which may extend margin credit to
the Funds as and when required to open or carry positions in the margin
accounts, subject to applicable Federal margin regulations, stock exchange rules
and the firm's credit policies. In such instances, the positions held in the
margin accounts are pledged as collateral security for the repayment of debit
balances in the accounts.

Item 4.   Purpose of Transaction.

     The purpose of the acquisition of the Shares by the Funds is for
investment. The Reporting Persons may cause the Funds to make further
acquisitions of Common Stock from time to time or to dispose of any or all of
the shares of Common Stock held by the Funds at any time.


                                       6




     The Reporting Persons are engaged in the investment business. In pursuing
this business, the Reporting Persons analyze the operations, capital structure
and markets of companies, including the Company, on a continuous basis through
analysis of documentation and discussions with knowledgeable industry and market
observers and with representatives of such companies (often at the invitation of
management). From time to time, one or more of the Reporting Persons may hold
discussions with third parties or with management of such companies in which the
Reporting Person may suggest or take a position with respect to potential
changes in the operations, management or capital structure of such companies as
a means of enhancing shareholder value. Such suggestions or positions may relate
to one or more of the transactions specified in clauses (a) through (j) of Item
4 of Schedule 13D of the Exchange Act, including, without limitation, such
matters as disposing of or selling all or a portion of the company or acquiring
another company or business, changing operating or marketing strategies,
adopting or not adopting certain types of anti-takeover measures and
restructuring the company's capitalization or dividend policy.

     Except as set forth above, the Reporting Persons do not have any present
plans or proposals that relate to or would result in any of the actions required
to be described in Item 4 of Schedule 13D. Each of the Reporting Persons may, at
any time, review or reconsider its position with respect to the Company and
formulate plans or proposals with respect to any of such matters, but has no
present intention of doing so.

Item 5.   Interest in Securities of the Issuer.

     (a) As of the date of this Schedule 13D, the Management Company
beneficially owns 2,900,000 shares of Common Stock. As of November 3, 2004,
these shares represented 8.5% of the total 34,273,859 shares of Common Stock
outstanding as reported in the Company's Quarterly Report on Form 10-Q for the
fiscal quarter ended September 30, 2004. The percentages used herein and in the
rest of this statement are calculated based upon this number of outstanding
shares.

     As of the date of this Schedule 13D, the Offshore Fund directly
beneficially owns 1,714,700 shares of Common Stock, which represents 5.0% of the
total outstanding shares.

     (b) The Management Company and Mr. Loeb share voting and dispositive power
over the 2,900,000 shares of Common Stock held by the Funds. The Management
Company, Mr. Loeb and the Offshore Fund share voting and dispositive power over
the 1,714,700 shares of Common Stock held by the Offshore Fund.

     (c) Schedule A hereto sets forth certain information with respect to
transactions by the Funds, at the direction of the Reporting Persons, in the
Common Stock during the past sixty days.


                                       7




     Schedule B hereto sets forth certain information with respect to
transactions by the Offshore Fund, at the direction of the Management Company
and Mr. Loeb, in the Common Stock during the past sixty days.

     All of the transactions set forth on Schedule A and Schedule B, except as
may be otherwise noted therein, were effected in open market purchases on the
New York Stock Exchange through the Primary Brokers.

     Except as set forth above and on Schedule A and Schedule B, during the last
sixty days there were no transactions in the Common Stock effected by the
Reporting Persons, nor, to the best of their knowledge, any of their directors,
executive officers, general partners or members.

     (d) Other than the Funds which directly hold the shares of Common Stock
reported herein, and except as set forth in this Item 5, no person is known to
have the right to receive or the power to direct the receipt of dividends from,
or the proceeds from the sale of, such shares.

Item 6.   Contracts, Arrangements, Understandings or Relationships With Respect
          to Securities of the Issuer.

     Pursuant to Rule 13d-1(k) promulgated under the Exchange Act, the Reporting
Persons have entered into an agreement with respect to the joint filing of this
statement, and any amendment or amendments hereto.

     By virtue of the relationships among the Reporting Persons and the Funds,
as described in Item 2, the Reporting Persons and the Funds may be deemed to be
a "group" under the Federal securities laws. Except as otherwise set forth in
this Schedule 13D, each Reporting Person expressly disclaims beneficial
ownership of any of the shares of Common Stock beneficially owned by any other
Reporting Person or the Funds and the filing of this Statement shall not be
construed as an admission, for the purposes of Sections 13(d) and 13(g) or under
any provision of the Exchange Act or the rules promulgated thereunder or for any
other purpose, that any Reporting Person is a beneficial owner of any such
shares.

     Except as set forth herein, there are no contracts, arrangements,
understandings or relationships among the persons named in Item 2 or between
such persons and any other person with respect to any securities of the Company.


                                       8




Item 7.   Material to be Filed as Exhibits.

     1. Joint Filing Agreement, dated as of February 7, 2005, by and between the
Reporting Persons.

             [THE REMAINDER OF THIS PAGE LEFT INTENTIONALLY BLANK.]


                                       9




                                   Schedule A
                                   ----------

                          (Transactions by the Funds in
                    Common Stock during the past sixty days)

------------------ ------------------- ----------------- -----------------------
       Date            Transaction          Shares           Price Per Share
------------------ ------------------- ----------------- -----------------------
    1/25/2005              BUY             1,500,000             28.0639
------------------ ------------------- ----------------- -----------------------
    1/25/2005              BUY              50,000               27.3800
------------------ ------------------- ----------------- -----------------------
    1/26/2005              BUY              660,000              29.9190
------------------ ------------------- ----------------- -----------------------
    1/26/2005              BUY              40,000               28.7244
------------------ ------------------- ----------------- -----------------------
    1/26/2005              BUY              25,000               29.5500
------------------ ------------------- ----------------- -----------------------
    1/27/2005              BUY              125,000              30.3251
------------------ ------------------- ----------------- -----------------------
     2/1/2005              BUY              64,100               30.4900
------------------ ------------------- ----------------- -----------------------
     2/2/2005              BUY              235,900              31.8555
------------------ ------------------- ----------------- -----------------------
     2/3/2005              BUY              100,000              32.9457
------------------ ------------------- ----------------- -----------------------
     2/4/2005              BUY              100,000              34.5627
------------------ ------------------- ----------------- -----------------------


                                   Schedule B
                                   ----------

             (Transactions by only the Offshore Fund in Common Stock
                           during the past sixty days)

------------------ ------------------- ----------------- -----------------------
       Date            Transaction         Shares            Price Per Share
------------------ ------------------- ----------------- -----------------------
    1/25/2005              BUY             861,300               28.0639
------------------ ------------------- ----------------- -----------------------
    1/25/2005              BUY             50,000                27.3800
------------------ ------------------- ----------------- -----------------------
    1/26/2005              BUY             384,400               29.9190
------------------ ------------------- ----------------- -----------------------
    1/26/2005              BUY             40,000                28.7244
------------------ ------------------- ----------------- -----------------------
    1/27/2005              BUY             73,300                30.3251
------------------ ------------------- ----------------- -----------------------
     2/1/2005              BUY             40,100                30.4900
------------------ ------------------- ----------------- -----------------------
     2/2/2005              BUY             151,100               31.8555
------------------ ------------------- ----------------- -----------------------
     2/3/2005              BUY             57,000                32.9457
------------------ ------------------- ----------------- -----------------------
     2/4/2005              BUY             57,500                34.5627
------------------ ------------------- ----------------- -----------------------




                                   SIGNATURES

     After reasonable inquiry and to the best of our knowledge and belief, the
undersigned certify that the information set forth in this statement is true,
complete and correct.


Dated: February 7, 2005


                                        THIRD POINT MANAGEMENT
                                        COMPANY L.L.C.

                                        By: /s/ Daniel S. Loeb
                                            ------------------------------
                                            Name:  Daniel S. Loeb
                                            Title: Managing Member


                                        THIRD POINT OFFSHORE FUND, LTD.

                                        By: /s/ Daniel S. Loeb
                                            ------------------------------
                                            Name:  Daniel S. Loeb
                                            Title: Director


                                        /s/ Daniel S. Loeb
                                        ------------------------------
                                        Daniel S. Loeb













                         [SIGNATURE PAGE TO SCHEDULE 13D
                     WITH RESPECT TO UNISOURCE ENERGY CORP.]