"Right now, it's not about me or my performance," said the Japanese right-hander, who has allowed four runs in each of his last four outings. "It's the fact that the team can get the win in the games that I start."

Jonathan Papelbon worked the ninth for his 35th save, and second in two nights.

Baltimore got runners on second and third with one out before Papelbon struck out Cesar Izturis and rookie Josh Bell.

With the victory, Boston salvaged what could have been a disastrous road trip. They lost two of three at the Tampa Bay Rays, then lost in Baltimore on Tuesday before winning the next two.

Adrian Beltre homered to spark a five-run second inning, David Ortiz drove in two runs and JD Drew had three hits for the Red Sox, who moved within 6 1/2 games of idle Tampa Bay in the American Leaguge wild-card race.

"We got off to a rough start on the road trip, but we were able to finish strong, win these last two," said Scott Atchison, who pitched two scoreless innings of relief. "We got some momentum going and hopefully we can take it home, get on a big roll. You never know what can happen from there."

Orioles manager Buck Showalter was denied his 900th career win for a second time.

Papelbon became the only pitcher in Major League Baseball history to record at least 35 saves in each of his first five seasons.

The Orioles trailed 5-0 and had been limited to two hits over the first five innings by Matsuzaka. The only runner against Matsuzaka in the first three innings was Luke Scott, who reached on an error but was then out on a double play.

But Baltimore chased Matsuzaka with a four-run sixth.

Nick Markakis hit an RBI single and Ty Wigginton followed with a run-scoring groundout before Matt Wieters hit a two-run double.

"It was the first time since I aggravated my back that I threw at full strength. I think there's a little adjustment there that I need to get over," Matsuzaka said. "In the sixth inning, I think I rushed a little bit."