"His back locked up a little bit on the right side," Girardi said. "I don't think it's anything serious, but it's the tough part about playing indoors sometimes.
"Sometimes that turf grabs at you a little bit."
Youkilis went 1-for-3 and, after striking out his first two at-bats, came through with a big hit off Blue Jays starter Mark Buehrle in the fifth inning. With one out and the bases loaded, Youkilis drilled a line drive at Blue Jays third baseman Brett Lawrie. It appeared to be a makeable play, but the ball ate Lawrie up and went into left field to score Jayson Nix easily and Brett Gardner, who slid home to beat Melky Cabrera's throw to the plate.
"It was a knuckleball and it just ended up getting away," Lawrie said about the play.
Girardi wanted to give some of his starters rest, because after the Yankees leave Toronto, they will play three more games on artificial turf against the Rays, bringing the total to six consecutive games on turf.
Nix is expected to get the start at third base Sunday, Girardi said.