Kevin Youkilis going for MRI

With Kevin Youkilis' back stiff again, Joe Girardi didn't include the veteran infielder in the lineup Sunday. On Monday, Youkilis will undergo an MRI to check the seriousness of his injury. He hasn't undergone any tests to this point.

Girardi tried to cure Youkilis' back problems by not playing him for a week. On Saturday, Youkilis returned, going 0-for-3 against Toronto and saying his back felt fine. On Sunday, Youkilis woke up and his back was tight again, according to Girardi.

"It is a little concerning for me," Girardi said. "I've said that all backs can be tricky. I'm a guy who has had to deal with it for a number of years. Sometimes you have no idea why it acts up."

By playing Youkilis on Saturday, the Yankees lost the ability to retro-activate a possible DL stint to last Sunday. If Youkilis had sat out on Saturday, then the Yankees could put him on the DL and have him return by May 6. Now, if Youkilis were put on the DL, he would have to miss games until at least May 13.

"He is an important guy to our lineup because he kind of surrounds some of the left-handed hitters and he is a production guy and he is a home run guy," Girardi said. "He is important, so we have to get this right. We can't push it too fast. If there are days that he is a little stiff, we may have to back off a little bit and try again the next day."

Youkilis is hitting .266 with two homers and seven RBIs in 17 games.

Youkilis was not in the clubhouse during media availability.