Mauer injured his hamstring while running the bases in Friday's 5-3 loss to the Brewers. He stayed in the game, but it got worse as the game went along, according to Twins manager Ron Gardenhire.
"Mauer has a little bit of a sore hamstring," Gardenhire said. "It happened last night in the game. So we'll back him off and we'll go day to day."
Mauer tried testing his hamstring before Saturday's game, but ultimately decided it would be best to give it a day of rest. Gardenhire said Mauer is available to pinch-hit, but would need a pinch-runner.
"It was barking on him last night pretty good," Gardenhire said. "He came in today and said he was feeling better, but when he went out there to run it was grabbing on him pretty good."
With Mauer out, Ryan Doumit started behind the plate for the Twins. Josh Willingham, who is dealing with a sore knee, served as designated hitter.