A.J. Burnett was forced to miss a start Sunday because of a bad back. Alex Rodriguez would not let a freak injury cause him to miss another game against the Boston Red Sox.

Burnett tweaked his back Saturday while working out on flat ground, but Yankees manager Joe Girardi said the right-hander was feeling much better after getting treatment.

He "felt his back tighten, spasms, stiffness and we just thought it was in our best interest to move him back 'til Tuesday," Girardi said. "The thing is he goes out and starts and feels it in the first, second or third inning it kind of puts us in a little bit of a bind."

Right-hander Dustin Moseley moved up a day to start against Boston on Sunday night. Phil Hughes will face Red Sox lefty Jon Lester in the series finale Monday.

Burnett, who will start Tuesday at Texas, was not available before Sunday's game.

Rodriguez, though, bounced back quickly from taking a sharp grounder off his left leg during batting practice Saturday. Rodriguez was down on the ground for a couple of minutes while he was attended to after Lance Berkman's grounder struck him. He missed New York's win and had X-rays, which were negative.

But Rodriguez walked without a limp into a lunch with a group of students Sunday afternoon and Girardi had the three-time MVP in the lineup posted in the clubhouse at 4:30 p.m. Girardi wouldn't commit to that lineup, though.

"I can't tell you that that will be out lineup at 8 o'clock," he said.

The slugger who hit his 600th homer Wednesday ran, hit and fielded grounders during batting practice to prove he was OK to play.

When Rodriguez was fielding grounders — his activity when he was dinged Saturday — Jorge Posada hit a ball well foul of the third-base line and Derek Jeter exaggerated a shout of "Look out!" and held his hand up.