McMahon will start at third base and bat seventh in Wednesday's game against the Pirates, Thomas Harding of MLB.com reports.
Nolan Arenado's five-game suspension will conclude after Wednesday's game, so McMahon will likely head back to a regular bench role when the Rockies return to Colorado for their series opener with the Cubs on Friday. Though he's been included in the lineup in five of the Rockies' past seven games, McMahon has recorded just three hits while striking out in half of his 18 at-bats during that span.