
<PAGE>
 
                                                                   EXHIBIT 10(c)


                   AMENDMENT TO PERSONAL SERVICES AGREEMENT

     This Amendment (this "AMENDMENT") to that certain Personal Services
Agreement and Acknowledgment of Termination of Executive Employment (the
"PERSONAL SERVICES AGREEMENT") is effective as of January 1, 1999 by and between
Ashworth, Inc., a Delaware corporation (the "COMPANY") and Gerald W. Montiel
("MONTIEL").

                                  BACKGROUND

     A.  Montiel retired from his position as Chairman of the Board of 
Directors of the Company effective December 31, 1998.

     B.  The Personal Services Agreement provides, among other things, that 
(i) Montiel will provide consulting services to the Board of Directors of the
Company and (ii) all options held by him shall become immediately exercisable
for a five-year period.

     C.  Montiel holds an option granted on October 2, 1993 under the Company's 
Amended and Restated Incentive Stock Option Plan (the "INCENTIVE PLAN") which
may not, by its terms and the terms of the Incentive Plan, remain exercisable
for a five-year post-retirement period (i.e., until December 31, 2004).

     D.  The parties wish to (i) terminate the option granted to Montiel on 
October 2, 1993 under the Incentive Plan, (ii) amend the terms of the Personal
Services Agreement to exclude such option from the list of options to be
exercisable for the five-year post-retirement period, and (iii) grant a new
option to Montiel under the Company's Amended and Restated Nonqualified Stock
Option Plan (the "NONQUALIFIED PLAN").

     NOW, THEREFORE, the parties agree as follows:

     1.  TERMINATION OF OPTION.  All outstanding stock options granted by the
         ---------------------                                               
Company to Montiel under the Incentive Plan on October 2, 1993 are hereby
terminated to the extent they have not yet been exercised.  The parties
acknowledge that one stock option to purchase 11,764 shares of the Company's
Common Stock at an exercise price of $8.50 per share is terminated by this
Section 1.
--------- 

     2.  AMENDMENT TO PERSONAL SERVICES AGREEMENT.
         ---------------------------------------- 

         a.  Section 8 (Stock Options) of the Personal Services Agreement is 
hereby deleted in its entirety and the following is inserted in lieu thereof:

     "8.  Stock Options.  All options held by Montiel shall become immediately
          -------------                                                       
          exercisable for a period of five years pursuant to the terms of the
          1995 Agreement.  The following is a list of the options:
<PAGE>
 
               GRANT DATE         OPTION PRICE        NO. OF SHARES
               ----------         ------------        -------------
                10/02/93             $ 8.50               133,236
                01/22/96             $ 6.50                15,384
                01/22/96             $ 6.50                 5,241
                11/11/97             $10.1875               1,132
                11/11/97             $10.1875              18,868
                11/11/97             $10.1875               9,815
                11/11/97             $10.1875              10,185
                11/11/97             $10.1875               9,815
                11/11/97             $10.1875              10,185
                                                        ---------
 
                Total Options                             213,861."


         b.  Except as expressly set forth in this Amendment all other terms of
the Personal Services Agreement shall remain in full force and effect.

     3.  GRANT OF OPTION.
         --------------- 

         a.  The Company hereby grants to Montiel a stock option (the "OPTION")
under the Nonqualified Plan to purchase shares of the Company's Common Stock
upon the following terms and conditions:

         Option Grant Date:                           January 1, 1999
     
         Maximum Number of Shares of Common
         Stock Issuable Upon Exercise of Option:      11,764
 
         Purchase Price Per Share:                    $8.50

         Vesting Schedule:                            Fully Vested

         Expiration Date:                             December 31, 2004


         b.  Montiel has received a copy of the Nonqualified Plan.  This
                                                                         
Section 3 is subject in all respects to the applicable provisions of the
---------                                                               
Nonqualified Plan, which are incorporated herein by reference.  In the case of
any conflict between the provisions of the Nonqualified Plan and this Section 3,
                                                                      --------- 
the provisions of the Nonqualified Plan shall control.

     4.  GOVERNING LAW.  This Agreement shall be governed by, interpreted 
         -------------
under, and construed and enforced in accordance with the internal laws, and not
the laws pertaining to conflicts or choice of laws, of the State of California
applicable to agreements made or to be performed wholly within the State of
California.

                                       2
<PAGE>
 
     5.  COUNTERPARTS.  This Amendment may be executed in any number of 
         ------------
counterparts, each of which shall be an original and all of which together shall
constitute one and the same instrument.


     6.  FACSIMILE.  This Amendment may be executed and delivered by facsimile
         ---------
and, upon such execution and delivery, shall have the same force and effect as
an originally executed instrument.

          IN WITNESS WHEREOF, the Company and Montiel have executed this 
Agreement effective as of the date first above written.



                              ASHWORTH, INC.,
                              A DELAWARE CORPORATION


                              By:  /s/ RANDALL L. HERREL
                                   -----------------------------------
                                   Randall L. Herrel
                                   President and Chief Executive Officer


 
                                   /s/ GERALD W. MONTIEL
                                   -----------------------------------
                                   Gerald W. Montiel

                                       3
