Plouffe injured his thumb during his third at-bat of the game in the seventh inning. He was jammed on an inside pitch from Royals right-hander Luke Hochevar and lined the ball back to the mound.
Plouffe was lifted in the ninth for pinch-hitter Brian Dozier, who struck out against reliever Greg Holland. Plouffe tried taking a few swings in the on-deck circle, but he couldn't feel anything in his thumb.
Plouffe, though, said the injury isn't serious and is something he's dealt without throughout his career, including most of this season.
"It's all right," Plouffe said. "It's something that's been kinda going on all year. Just some tenderness in the thumb area from letting the ball get deep. I've been playing with it all year, but tonight it just was more direct. Basically I just got jammed really good."
Plouffe said he expects he'll only need to miss one game, while manager Ron Gardenhire said they'll continue to monitor the situation this weekend.
"We've all done that as a hitter -- you get a deep bone bruise right in there and it's pretty painful." Gardenhire said. "So we'll give him a day or two with a little ice and treatment, and he should be back in there."
Dozier moved to shortstop for the bottom of the inning with Jamey Carroll moving from shortstop to third base.