Kevin Youkilis exits with jammed thumb

BOSTON -- There have been times, especially when he knew that his first baseman was unharmed, that Red Sox manager Terry Francona has kidded about Kevin Youkilis' demonstrative reactions after, say, being hit by a pitch or otherwise feeling temporary discomfort.

This was not one of those times. When Youkilis yelped in pain after being jammed in the first inning while lining a ball to short, Francona was sufficiently concerned that he removed Youkilis from the game before the start of the third.

X-rays taken of Youkilis's jammed right thumb were negative, but Francona said after the game that Youkilis will undergo an MRI exam on Tuesday. He did not say whether he thought Youkilis would be available to play Tuesday night against the Cleveland Indians, nor whether the injury could sideline him longer than that.

"He's pretty sore," Francona said following a 6-5 loss to the Indians. "He has a bone bruise in that area, and when he got jammed, that thing swelled up real quick and got discolored.

"So he came upstairs and got under the fluoroscan, and that was negative, but we are going to send him in the morning to get an MRI just to see if there is anything going on."

Youkilis immediately reacted with pain after lining out to short to end the bottom of the first. Francona and trainer Mike Reinold checked him after the at-bat, but Youkilis remained in the game for the Cleveland second, and did not handle a chance.

Youkilis was not in the clubhouse when reporters were allowed entry after the game, but he returned to the dugout during the game and sat at the far end, cheering on his teammates.

Youkilis has started all but seven of Boston's 106 games this season, and his .307 average is second on the club to Adrian Beltre's .336. He also is second to Beltre, who hit two home runs Monday night, in slugging percentage (.567 to .564), and is tied for second in home runs with Beltre (19), behind David Ortiz's 22. His on-base percentage of .411 ranks third in the American League, behind only Justin Morneau (.437) of the Twins and Miguel Cabrera (.429) of the Tigers.

Victor Martinez, who began the game behind the plate, moved to first base when Youkilis was removed at the start of the third, with Kevin Cash taking over as catcher. When Francona hit for Cash in the eighth with Jed Lowrie, Martinez returned behind the plate for the ninth inning, with Lowrie making his big league debut at first. He handled a throw and ground ball cleanly.

Gordon Edes covers the Red Sox for ESPNBoston.com.