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04/13/09 5:51 PM ET

Moehler to have MRI on right knee

Astros righty exits Monday start early with lingering injury

PITTSBURGH -- The Astros may have added injury to insult on Monday afternoon.

In addition to losing their fifth straight, they may have to deal with not having starter Brian Moehler's services for a while. The right-hander left Monday's game in the third inning with a right knee sprain and will have an MRI in Pittsburgh on Tuesday.

"It's one of those things that's been bugging me a little bit," Moehler said. "It's been an off and on thing for a few weeks now."

Moehler is now 0-2 with a 27.00 ERA in his two starts. He gave up seven runs in 1 2/3 innings against the Cubs in his first start and was charged with five more in 2 1/3 frames vs. the Bucs. It now seems evident the knee may at least have contributed to the poor outings.

"It's in a bad spot, because it's my push-off leg," Moehler said. "I'm just not able to drive the ball like I'd like to. That presents a problem when you're a pitcher.

"It's aggravating. When I throw, I can feel it. When you try to push off your back leg, it's there. Hopefully tomorrow, the tests will show nothing major, but we'll get it taken care of."

Moehler's next start is slated to be Sunday against the Reds in Houston. The Astros will await the results of Tuesday's test before making any announcement about that turn in the rotation.

Jonathan Mayo is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.