SECURITIES & EXCHANGE COMMISSION Washington, D.C. 20549 ---------------------- SCHEDULE 13G (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1(b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO 13d-2(b) (Amendment No. __)* UNISOURCE ENERGY CORPORATION (Name of Issuer) Common Stock, No Par Value (Title of Class of Securities) 909205106 (CUSIP Number) August 9, 2005 (Date of event which requires filing of this statement) Check the appropriate box to designate the rule pursuant to which this Schedule 13G is filed: [ ] Rule 13d-1(b) [X] Rule 13d-1(c) [ ] Rule 13d-1(d) (Page 1 of 13 Pages) --------------- *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 the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for purposes 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). CUSIP No. 909205106 13G Page 2 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) SAB CAPITAL PARTNERS, L.P. ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,137,061 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 1,137,061 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,137,061 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 3.3% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** PN ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 909205106 13G Page 3 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) SAB CAPITAL PARTNERS II, L.P. ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 21,473 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 21,473 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 21,473 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 0.1% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** PN ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 909205106 13G Page 4 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) SAB OVERSEAS MASTER FUND, L.P. ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,231,766 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 1,231,766 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,231,766 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 3.5% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** PN ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 909205106 13G Page 5 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) SAB CAPITAL ADVISORS, L.L.C. ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 2,390,300 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 2,390,300 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,390,300 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.9% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** 00 ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 909205106 13G Page 6 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) SCOTT A BOMMER ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States of America ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 2,390,300 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 2,390,300 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,390,300 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 6.9% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** IN ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 909205106 13G Page 7 of 12 Pages Item 1(a). Name of Issuer: The name of the issuer is UNISOURCE ENERGY CORPORATION (the "Company"). Item 1(b). Address of Issuer's Principal Executive Offices: The Company's principal executive office is located at One South Church Avenue, Suite 100, Tucson, AZ 85701 Item 2(a). Name of Person Filing: This statement is filed by: (i) SAB Capital Partners, L.P., a Delaware limited partnership ("SAB"), with respect to shares of Common Stock (as defined in Item 2(d) below) directly owned by it; (ii) SAB Capital Partners II, L.P., a Delaware limited partnership ("SAB II", and together with SAB, the "Domestic Partnerships"), with respect to shares of Common Stock (as defined in Item 2(d) below) directly owned by it; (iii) SAB Overseas Master Fund, L.P., a Cayman Islands exempted limited partnership (the "Master Fund"), with respect to shares of Common Stock (as defined in Item 2(d) below) directly owned by it; (iv) SAB Capital Advisors, L.L.C., a Delaware Limited Liability Company (the "General Partner"), which serves as the general partner of each of the Domestic Partnerships and the Master Fund, with respect to shares of Common Stock (as defined in Item 2(d) below) directly owned by each of the Partnerships and the Master Fund; (v) Mr. Scott A. Bommer ("Mr. Bommer"), who serves as the managing member of the General Partner with respect to shares of Common Stock directly owned by the Partnerships and the Master Fund. The Domestic Partnerships, the Master Fund, the General Partner, and Mr. Bommer are hereinafter sometimes collectively referred to as the "Reporting Persons." Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party. CUSIP No. 909205106 13G Page 8 of 12 Pages Item 2(b). Address of Principal Business Office or, if None, Residence: The address of the business office of each of the Reporting Persons is 712 Fifth Avenue, 42nd Floor, New York, N.Y. 10019. Item 2(c). Citizenship: Each of the Domestic Partnerships and the General Partner, is organized under the laws of the State of Delaware. The Master Fund is an exempted limited partnership organized under the laws of the Cayman Islands. Mr. Bommer is a citizen of the United States of America. Item 2(d). Title of Class of Securities: Common Stock, No Par Value (the "Common Stock") Item 2(e). CUSIP Number: 909205106 Item 3. If this statement is filed pursuant to Rules 13d-1(b) or 13d-2(b) or (c), check whether the person filing is a: (a) [ ] Broker or dealer registered under Section 15 of the Act, (b) [ ] Bank as defined in Section 3(a)(6) of the Act, (c) [ ] Insurance Company as defined in Section 3(a)(19) of the Act, (d) [ ] Investment Company registered under Section 8 of the Investment Company Act of 1940, (e) [ ] Investment Adviser in accordance with Rule 13d-1(b)(1)(ii)(E), (f) [ ] Employee Benefit Plan or Endowment Fund in accordance with Rule 13d-1(b)(1)(ii)(F), (g) [ ] Parent Holding Company or control person in accordance with Rule 13d-1(b)(1)(ii)(G), (h) [ ] Savings Association as defined in Section 3(b) of the Federal Deposit Insurance Act, (i) [ ] Church Plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act of 1940, (j) [ ] Group, in accordance with Rule 13d-1(b)(1)(ii)(J). If this statement is filed pursuant to 13d-1(c), check this box: [x] CUSIP No. 909205106 13G Page 9 of 12 Pages Item 4. Ownership. A. SAB Capital Partners, L.P. (a) Amount beneficially owned: 1,137,061 (b) Percent of class: 3.3% The percentages used herein and in the rest of this Schedule 13G are calculated based upon the 34,706,932 shares of Common Stock issued and outstanding on August 4, 2005, as reflected in the Company's Form 10Q for the Quarterly period ended June 30, 2005. (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 1,137,061 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 1,137,061 B. SAB Capital Partners II, L.P. (a) Amount beneficially owned: 21,473 (b) Percent of class: 0.1% (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 21,473 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 21,473 C. SAB Overseas Master Fund, L.P. (a) Amount beneficially owned: 1,231,766 (b) Percent of class: 3.5% (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 1,231,766 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 1,231,766 D. SAB Capital Advisors, L.L.C. (a) Amount beneficially owned: 2,390,300 (b) Percent of class: 6.9% (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 2,390,300 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 2,390,300 CUSIP No. 909205106 13G Page 10 of 12 Pages E. Scott A. Bommer (a) Amount beneficially owned: 2,390,300 (b) Percent of class: 6.9% (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 2,390,300 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 2,390,300 Item 5. Ownership of Five Percent or Less of a Class. Not applicable. Item 6. Ownership of More than Five Percent on Behalf of Another Person. Not applicable. Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company. Not applicable. Item 8. Identification and Classification of Members of the Group. See Item 2. Item 9. Notice of Dissolution of Group. Not applicable. CUSIP No. 909205106 13G Page 11 of 12 Pages Item 10. Certification. Each of the Reporting Persons hereby makes the following certification: By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. DATED: August 19, 2005 /S/ Scott A Bommer ------------------------------------- Scott A Bommer, individually and as managing member of (a) SAB Capital Advisors, L.L.C., for itself and as the general partner of (i) SAB Capital Partners, L.P. and (ii) SAB Capital Partners II, L.P.; and (iii) SAB Overseas Master Fund, L.P. CUSIP No. 909205106 13G Page 12 of 12 Pages EXHIBIT 1 JOINT ACQUISITION STATEMENT PURSUANT TO RULE 13d-1(k) The undersigned acknowledge and agree that the foregoing statement on Schedule 13G, is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G, shall be filed on behalf of each of the undersigned without the necessity of filing additional joint acquisition statements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate. DATED: August 19, 2005 /S/ Scott A Bommer ------------------------------------- Scott A Bommer, individually and as managing member of (a) SAB Capital Advisors, L.L.C., for itself and as the general partner of (i) SAB Capital Partners, L.P. and (ii) SAB Capital Partners II, L.P.; and (iii) SAB Overseas Master Fund, L.P.