CHICAGO -- White Sox starting pitcher Jake Peavy left Tuesday's start against the Angels in the second inning with a strained right back muscle.
The team said Peavy will have an MRI on his arm and upper back on Wednesday.
"Unfortunately we have to wait until tomorrow to see how he feels. When you take yourself out of the game like that it's never anything good. I got to wait to see what the doctors think and then we will figure what to do. I'm pretty sure right now I think he is going to be on the DL. I will talk to [general manager] Kenny [Williams] about it," said manager Ozzie Guillen.
The White Sox were leading 1-0 with two outs in the inning when Peavy delivered a 2-2 pitch to the Angels' Mike Napoli. Peavy jumped off the mound and raised his right arm, then walked straight to the dugout with team trainer Herm Schneider.
Peavy said he feels pain on the top of his armpit and said he also experienced discomfort in his last start at Kansas City on June 30.
"I felt something in my last start. We had something going on, some bruising in this area after my last start that we saw and treated. I saw the doctor, and had a little strain in there that we treated. [I] played a little catch and knew I was going to feel it tonight and did a little bit. Obviously I did more than feel it on that one pitch and I knew I was done," said Peavy.
He was asked if this was a related injury.
"I can't tell," he said. "I certainly don't know. I really can't. I'll have an MRI [Wednesday] and see our doctors, and just go from there."
The White Sox's pitcher says he isn't sure how long he'll be out.
"It's something up under my arm and it goes down into my lat," Peavy said. "That's where I have some swelling and discomfort. That's where I felt it happen tonight."
The White Sox contemplated skipping Peavy's turn in the rotation on June 17 at Pittsburgh because of an achy right shoulder, but after an MRI showed no damage, Peavy insisted on pitching two days later against Washington. In that game, he tossed a three-hitter for his fourth career shutout.
"When you throw a pitch and you feel the way I felt during and after that pitch it's just something I can't go on," Peavy said.
Peavy has had numerous traumas to his arm during his career -- including a strained right forearm in 2004 and a strained right elbow in 2008. Both injuries landed him on the DL. Peavy missed three months in 2009 with a strained right ankle.
After a slow start to his season, Peavy has been a key to the White Sox's resurgence. He had a 3-2 record with a 1.75 ERA in June. On the season, he is 7-6 with a 4.63 ERA.
Bruce Levine covers baseball for ESPNChicago.com. Information from The Associated Press contributed to this report.