BOSTON – Red Sox reliever Mike Timlin was placed on the 15-day disabled list Saturday because of tendinitis in his left knee, the fifth time in the last three seasons Timlin has been on the disabled list.

The move allowed Boston to activate right-hander Daisuke Matsuzaka, who started against the St. Louis Cardinals.

The 42-year-old Timlin, placed on the DL retroactive to June 17, is 3-3 with a 7.06 ERA in 24 relief appearances this season. He also began this season on the disabled list with a bruised right index finger, and was on the DL twice in 2007 – once for a strained left oblique muscle and once with right shoulder tendinitis.

“It's starting to get a little bit worse. We figured this would be a good time to take some time and let it cool down,” he said. “It's been around a while. It's not something that's brand new. Every athlete plays with pain. You just do.”

But he wouldn't use the injury as a reason for his poor showings so far.

“To me, that's an excuse, and I don't make excuses,” he said. “I've just pitched badly. I can't blame it on anything else but my performance.”

Boston manager Terry Francona felt Timlin had been pitching better of late.

“I think you have to look a little bit beyond the numbers,” he said. “Last year, when he first came back, he wasn't really throwing that well. He was getting people out and he wasn't really hitting his spots a lot but started getting people out and then his confidence grew and then he really did start throwing well.

“Now, it's kind of funny,” Francona said. “The ball seems to be coming out of his hand pretty good, but when does miss his spots, he's paying for it. The good news is that he doesn't look like he's hurting, but there has been a lot of inconsistencies there in his pitching.”

Matsuzaka started for the first time since May 27, when he suffered a mild strain of his right rotator cuff in Seattle.