McMahon will start at first base and bat eighth Sunday against the Dodgers, Patrick Saunders of The Denver Post reports.
Though he'll be included in the lineup for the series finale while veterans Carlos Gonzalez and Gerardo Parra rest, McMahon's days an everyday player came to an end for the time being following DJ LeMahieu's reinstatement from the disabled list Friday. McMahon, who was on the bench for the past two days, has gone 7-for-20 with three doubles since being promoted from Triple-A Albuquerque just over a week ago.