"The Red Sox placed Daisuke Matsuzaka on the 15-day disabled list yesterday, retroactive to Tuesday, but the righthander could be out at least a month after an MRI Tuesday confirmed he had a sprained ligament in his elbow.

Matsuzaka experienced tightness during his last start, a no-decision in an 8-7 victory over the Orioles Monday in which he lasted 4 1/3 innings and allowed five runs on five hits and seven walks.

"In general, I could hold the pain and still continue to throw before, but at this point I can't really,'' Matsuzaka said through an interpreter. "It's difficult to hold it and throw with this kind of pain. So I usually have a very high tolerance, but this time it's hard for me to keep throwing.''"