Mietkiewicz suffered the injury in the eighth inning while fielding an infield single by J.J. Hardy.
"I pulled my left hip and groin on the slow roller," Mientkiewicz reported. "I've never pulled anything in my life, and [it is] something you've got to play through. I told the manager I'm ready to go and we'll see what happens.
The veteran Mientkiewicz is trying to serve as a role model for his younger teammates.
"I think it's important to show the guys around here that sometimes you have to play through things and that's part of the game," he said. "You have to understand that not everybody is 100 percent, but hopefully I'll get a chance to go in there."
Mientkiewicz was not in the starting lineup in the series finale vs. the Brewers on Sunday.
George Von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.