"It has been nearly three weeks since Daisuke Matsuzaka walked off the mound at Fenway Park in the fifth inning of a start against the Seattle Mariners because of stiffness in his right elbow.

Now, the right-hander is about to be placed on the disabled list.

It's not clear whether Matsuzaka's elbow sprain, revealed yesterday by an MRI exam, is related to the discomfort he felt on April 29, although Red Sox manager Terry Francona said "it's hard to imagine it's not." Regardless, the Sox will be without Matsuzaka for at least 15 days — and likely longer.

"We're going to shut him down for a period of whatever time we need," Francona said after rain postponed last night's game against the Baltimore Orioles at Fenway. "If you put a time period out there, it's not fair to Daisuke. The doctors don't even know."

The move will be official before tonight's series opener against the Detroit Tigers, at which time the Red Sox also will recall reliever Michael Bowden from Triple-A Pawtucket. Bowden joined the team yesterday.

Alfredo Aceves, a righty who has been used as a long reliever, will enter the starting rotation and pitch Saturday night against the Chicago Cubs. Knuckleballer Tim Wakefield, scheduled to start last night in place of injured righty John Lackey (elbow strain), instead will start Sunday against the Cubs."