Jed Lowrie's two-run triple highlighted a three-run fourth inning that helped Daisuke Matsuzaka to his 12th win and the Boston Red Sox completed a three-game sweep with a 5-2 win over the struggling Oakland Athletics on Sunday.

Jason Bay continued his strong start with the Red Sox since being acquired in a three-team, last-minute trade deadline deal for Manny Ramirez on Thursday, going 2-for-4 with a pair of singles and two runs scored. He also threw out a runner trying to stretch a single.

Boston improved to 40-16 at Fenway Park after losing five of the initial six games in a nine-game homestand. The Red Sox, just 24-32 away from home, play their next seven games on the road, beginning Monday night in Kansas City.

Daric Barton hit a two-run homer for the Athletics, who lost their sixth straight and 15th in 17 games.

Matsuzaka (12-2), allowed two runs, four hits, walked two and struck out eight in six innings.

Jonathan Papelbon, the third reliever, worked a perfect ninth for his 31st save. Boston's bullpen held the A's to one single over the final three innings.

The Red Sox grabbed a 1-0 lead five pitches into the game when Dustin Pedroia doubled off the Green Monster and scored on Kevin Youkilis' single.

Boston increased it to 4-0 and chased starter Dallas Braden (2-2) in the fourth. Lowrie, the final batter Braden faced, hit a line drive over center fielder Carlos Gonzalez after Mike Lowell doubled and Bay singled. Gonzalez, playing shallow, had the ball go over his head as he broke back. Coco Crisp added a sacrifice fly.

Barton's homer cut it to 4-2 in the fifth.

Crisp's sacrifice fly made it 5-2 in the sixth.

Matsuzaka worked out of a tough spot in the second, allowing Gonzalez's leadoff triple before striking out Jack Hannahan and Bobby Crosby and getting Barton to fly out.

There was a lighter moment in the fifth when lumbering DH David Ortiz walked and took off for second on the next pitch, not drawing a throw on his first stolen base of the season that amused the crowd as catcher Rob Bowen bobbled the ball.

Notes:@ Boston RF J.D. Drew was given the day off. ... Red Sox RHP David Aardsma, on the 15-day DL since July 20 with a strained right groin, pitched a perfect inning with two strikeouts in a rehab assignment with Triple-A Pawtucket on Sunday afternoon. ... The A's optioned Saturday's losing pitcher Dana Eveland to Triple-A Sacramento before the game and recalled LHP Dan Meyer, who pitched a perfect eighth. ... A young boy seated along the third-base line was hit by Bay's foul liner in the fourth and quickly carried from the stands by a Red Sox security person. He was treated in a first-aid room in the park and later returned to his seat, team spokesperson John Blake said. ... Thunder rumbled around Fenway in the sixth, drawing 'oohs' from the crowd before play was halted by rain for 37 minutes. ... Ortiz had three stolen bases last season, his last Sept. 2. ... Youkilis has a 10-game hitting streak.