BALTIMORE — Daisuke Matsuzaka was placed on the 15-day disabled list today by the Boston Red Sox, who opted to take a cautious approach after an MRI exam revealed a mild strain of his right rotator cuff.

Matsuzaka was examined in Boston by Dr. Thomas Gill. It is the first trip to the disabled list by Matsuzaka, who joined the Red Sox last season after pitching in Japan.

"The real good news is there were no structural changes," Boston manager Terry Francona said. "The best way we can see to attack this, we'll DL him, take the time down and get him ready to pitch the rest of the season. That's kind of where we are."

The move was retroactive to Wednesday.

Francona said Matsuzaka put up a mild protest, hoping to pitch through the injury.

"I think that's first of all good news because it means he feels good about himself," the manager said. "That's what good pitchers and good players do. That's part of the reason they're good."

Matsuzaka is 8-0 with a 2.53 ERA in 11 starts this season. Opponents are batting .195 against him.

To replace Matsuzaka on the roster, the Red Sox recalled first baseman Jeff Bailey from Triple-A Pawtucket.