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                                                                   Exhibit 10.10


                                                  August 8, 2001


Mr. Thomas J. Usher
600 Grant Street
Suite 6100
Pittsburgh, PA 15219-4776

Dear Tom,

In connection with the separation of the businesses of the U.S. Steel Group and
Marathon Group pursuant to the Agreement and Plan of Reorganization approved by
the Board of Directors on July 31, 2001 (Separation) and your agreement to serve
as  Chairman, Chief Executive Officer and President of United States Steel
Corporation (USSC), Chairman of the Board of Directors of Marathon Oil
Corporation (Marathon) and Chairman of the Board of Managers of Marathon Ashland
Petroleum LLC (MAP), I am authorized to extend to you, on behalf of Compensation
Committee of USX Corporation (USX), this Completion and Retention Agreement
(Agreement), effective as of the date stated above.

The terms and conditions of our Agreement are as follows.

1.   If the Separation occurs, you will receive a salary  from USSC of
     $1,100,000 for each of years 2002 through 2004, subject to adjustment by
     the Board of Directors of USSC, or a committee thereof.

2.   Subject to the completion of the Separation, you will receive:

     (a)  a restructuring completion bonus of $6,000,000 payable by Marathon on
          the first business day after the effective time of the Separation; and

     (b)  a retention bonus payable by USSC on the third anniversary of the
          effective time of the Separation.  This retention bonus is capped at
          $3,000,000 and is further subject to the following performance
          measures and limitations authorized in (i) and (ii) below.

          (i)  On the third anniversary of the effective time of the Separation,
               (A) the fair value of the aggregate assets of USSC exceeds its
               total liabilities, (B) the fair saleable value of the aggregate
               assets of USSC exceed its probable liabilities, and (C) USSC is
               able to pay and discharge its debts and other liabilities as they
               become due.  The satisfaction of the foregoing performance
               measures shall be determined solely by the Board of Directors of
               USSC, or the Compensation Committee thereof.

          (ii) In the event the conditions under 2(b)(i) are satisfied, the
               retention bonus of $3,000,000 shall be further subject to the
               performance-related vesting criteria applicable to restricted
               stock under the USSC 2002 Stock Plan (Plan).  Based on a three-
               year rolling
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               average of comparator-company performances and the performance
               criteria established in Appendix A to the Plan, the Compensation
               Committee shall determine the percentage (not to exceed 100%) to
               be applied to the $3,000,000 retention bonus.

3.   Subject to completion of the Separation and in addition to the normal
     director fees paid to non-employee directors, you will receive a $25,000
     annual fee from Marathon for serving as Chairman of the Board of Marathon
     and Chairman of the MAP Board of Managers.

4.   A grant of 90,000 restricted shares of USX-Marathon Group Common Stock with
     (a) 30,000 shares subject to vesting on the first anniversary hereof based
     on the 2001 performance of USX under the USX Stock Plan as determined by
     the Compensation Committee on May 2, 2002, (b) 30,000 shares subject to
     vesting in May 2003 based on the 2002 performance of Marathon under the
     Marathon Stock Plan as determined by the Marathon Compensation Committee in
     May 2003, and (c) 30,000 shares subject to vesting in May 2004 based on the
     2003 performance of Marathon under the Marathon Stock Plan as determined by
     the Marathon Compensation Committee in May 2004.

5.   Subject to the completion of the Separation, a grant of phantom stock
     appreciation rights for 500,000 shares of Marathon common stock.  The
     exercise price of 150,000 shares will be based on the average of the high
     and low market price of USX-Marathon Group Stock Common Stock on the last
     trading day before the effective time of the Separation, and the exercise
     price of 350,000 shares will be based on the average of the high and low
     market price of Marathon common stock on the first trading day after the
     effective time of the Separation.  The effective date of each grant will be
     the same date as the determination of the exercise price.  These stock
     appreciation rights will vest on the effective date of the grant and will
     expire on the earlier of ten years from the effective date of grant, nine
     years following retirement or three years following death while employed.
     These rights will be paid in cash upon exercise.

6.   Subject to completion of the Separation, if you elect to receive your non-
     qualified pension plan as a lump sum distribution, the applicable interest
     rate and mortality table in effect for retirements on December 31, 2001
     will be used to calculate the amount of such pension instead of the
     applicable interest rate and mortality table in effect at the time of your
     retirement, which could be greater or less than such rate.

7.   Other provisions.  The following provisions are further subject to the
     ----------------
     completion of the Separation.

     (a)  In the event of any merger, consolidation or other business
          combination involving USSC which has not been approved by the Board of
          Directors of USSC, all benefits payable hereunder shall immediately
          become due and payable.

     (b)  This Agreement shall be binding upon and inure to the benefit of the
          parties hereto and their respective successors and assigns.  Your
          rights hereunder are not assignable.  We may assign our rights or a
          portion thereof to USSC or to any successor to USSC in a transaction
          approved by the Board of Directors of USSC.

     (c)  Except as otherwise provided herein, in the event of your death prior
          to the satisfaction of any benefit payable hereunder, any such benefit
          that

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          remains unsatisfied at such date shall immediately become due and
          payable, including the vesting of any restricted stock or stock
          appreciation rights.

     (d)  In the event that you voluntarily leave the employment of USSC on or
          before December 31, 2004, the benefits payable under paragraphs 1 and
          3 hereof shall be pro-rated based on the time elapsed.

     (e)  You agree that you will dedicate your full attention and efforts to
          the management and direction of both Marathon and USSC and that you
          will be diligent in acting in the best interests of these
          organizations.

     (f)  We reserve the right to terminate this Agreement for good cause.

Except for your salary set forth in paragraph 1 hereof, it is further understood
that the foregoing benefits are not benefit bearing under any tax-qualified or
non tax-qualified plan of USX, Marathon, USSC or MAP.

Because of your extensive experience and personal qualities, you can make a
unique and valuable contribution to the future of Marathon and USSC.  If the
terms and conditions herein are acceptable, please sign below.


                                        Sincerely,

                                        USX CORPORATION


                                        By: /s/ Seth E. Schofield
                                           -----------------------------
                                             Seth E. Schofield
                                              On Behalf of the
                                              Compensation Committee
                                              Of USX Corporation,
                                              predecessor to Marathon
                                              Oil Corporation


Agreed to and Accepted this 8th day of August, 2001.


/s/ Thomas J. Usher
--------------------------
     Thomas J. Usher


UNITED STATES STEEL LLC, predecessor
to United States Steel Corporation

Agreed to and Acknowledged

By: /s/ E. F. Guna
   -----------------------
Name:  E. F. Guna
     --------------------
Title: Vice President
      -------------------
Date:  August 8, 2001
     --------------------
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