BOSTON -- Another night, another starting pitcher heading to the disabled list. A day after John Lackey was shut down with a right elbow strain, right-hander Daisuke Matsuzaka is Boston's latest rotation member headed to the 15-day DL.

Matsuzaka underwent an MRI on Tuesday, and the diagnosis is that he has a sprained right elbow. Because Tuesday night's game was rained out, Boston will officially place Matsuzaka on the DL prior to Wednesday's game. To replace Matsuzaka on the roster, the Red Sox have summoned right-hander Michael Bowden from Triple-A Pawtucket.

On Wednesday, Red Sox medical director Dr. Tom Gill issued a statement:

"Daisuke experienced tightness in his elbow during his last start. His examination is consistent with a sprained ulnar collateral ligament, and strain to his common flexor mass. An MRI was obtained which confirmed these exam findings. He will be re-examined in two weeks."

The news came one day after Matsuzaka was shaky in Monday night's no-decision against the Orioles, walking seven and allowing five hits and five runs over 4 1/3 innings.

Bowden will work out of the bullpen. Alfredo Aceves and Tim Wakefield, who are starting on Saturday and Sunday respectively against the Cubs, will fill the two rotation spots.

As for Matsuzaka, he has been hesitant to use his fastball of late, perhaps a sign that he didn't have confidence in his health.

Dice-K is 3-3 with a 5.30 ERA this season. He was removed from his April 29 start against the Mariners with elbow tightness.

"It's hard to imagine it's not [related]," manager Terry Francona said. "But those are some of the same questions we tried to ask. Certainly you want to find out and learn, but we really just don't know. I don't think Daisuke knows. The reason we kind of did this, I think I said last night, he was guarded. Does he have pain? I don't think he really did, but I think he was guarded because he thought he might have pain. We figured we better check. I'm glad we did."

While the Red Sox have played well of late, winning four in a row, Francona was trying to take the positive out of two of his starting pitchers being shut down within two days.

"It doesn't change anything in our view," Francona said. "We're going to get Lack healthy and get him back out there as quick as we can. We're going to do the same thing with Daisuke. Until we do, we're going to try to win with somebody else. That's the way we always feel."

Bowden excited to be back in Sox's bullpen

BOSTON -- In a familiar scene, Michael Bowden reappeared on Tuesday. When he is officially recalled from Triple-A Pawtucket in time for Wednesday night's game against the Tigers, it will mark his eighth stint on the Red Sox's roster since 2008.

Once viewed as a starting pitching prospect, Bowden is now a full-fledged reliever.

In 14 games for Pawtucket, Bowden is 1-0 with a 1.59 ERA. He has four walks and 28 strikeouts in 22 2/3 innings.

"I've adapted to the bullpen role very well," said Bowden. "I feel good, I'm confident out of the bullpen, I'm throwing the ball well. I'm just excited to be here."

Bowden's transition to reliever actually started in the middle of last season. He made 14 appearances for the Red Sox last year, all in relief, posting a 4.70 ERA.

"Oh, it helped me a bunch," Bowden said. "Every day going out there, talking to the guys, seeing what they do and getting accustomed to it and adapting to that role, every day you go out there, you feel more and more comfortable, so I believe that will help me out a lot."

Wheeler expected to return to roster Friday

BOSTON -- The Red Sox expect to have Dan Wheeler back in their bullpen on Friday, the first day he is eligible to come off the 15-day disabled list.

Wheeler is out with a left calf strain. His return comes at a good time, given that relievers Alfredo Aceves and Tim Wakefield are in the process of moving to the rotation to replace injured starters John Lackey and Daisuke Matsuzaka.

"[Matt] Albers has done a terrific job and we certainly have [Daniel] Bard," said manager Terry Francona. "But it's nice to have another guy and I think we all, when we signed Wheeler, we hoped that's what he would fill -- and we still feel that way."

Another pitcher the Red Sox expected big things from this season is Bobby Jenks, who is also making progress during his stint on the DL. Jenks hasn't pitched since May 1 because of a right biceps strain.

"Jenks threw today, 60 feet," said Francona. "Good intensity. He'll move back a little farther tomorrow. He did very well. That's good."