BOSTON -- Brandon McCarthy just followed the blueprint that his rookie teammate provided one night earlier.
Coming one day after Jarrod Parker held the Red Sox to four hits in 6 2/3 innings for his first big-league victory, McCarthy held Boston's lineup to five hits in his outing.
"If anything, it gives you the confidence that you're not facing a team that scored a bunch of runs," McCarthy said of watching his teammate's success the previous game. "When you see someone go out there, throw strike one, with good location, I think it can give you the confidence that it can be done."
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Seth Smith drove in a pair of runs for Oakland. The A's, who started the day with the majors' worst batting average and fewest runs in the AL, took two of three games from the Red Sox.
Oakland moved back to the .500 mark after losing two of three in Baltimore.
"For us to win two of three shows the resiliency of this club," A's manager Bob Melvin said.
Boston has lost seven of its past eight in Fenway Park.
McCarthy (2-3) walked three and fanned four. He improved to 8-0 with a 3.34 ERA since 2009 against AL East clubs.
Brian Fuentes gave up Dustin Pedroia's RBI double in the ninth, but got his first save. He became the sixth lefty in major league history to collect his 200th career save.
After losing his job as the closer last summer, Fuentes couldn't remember when he collected his last one.
"I was stuck on 199 for a long time," Fuentes said, smiling. "We had a comfortable lead and the game played out well."
Daniel Bard (2-3) took the loss, allowing four runs on eight hits over 5 1/3 innings.
Red Sox third baseman Will Middlebrooks, recalled earlier in the day when Kevin Youkilis was placed on the 15-day DL with a strained lower back, went 2 for 3 with a double and a stolen base in his first major league game.
Boston's Adrian Gonzalez struck out with the bases loaded to close the seventh and bounced out to end the game. He went 0 for 4 and is hitless for his past 15 at-bats.
"This game is all on me. I had two great opportunities and I didn't come through," he said. "It's one of those things that I'm going to make a definite point to not let that happen again."
David Ortiz went 2 for 4 and is hitting .488 in Fenway, but it did little to help Boston's offense with Gonzalez struggling in front of him.
"I think he's just tired," Boston manager Bobby Valentine said of Gonzalez. "He's played the entire time and his timing recognition of the strike zone is just a little off."
Bard breezed through the first three innings, allowing only Cliff Pennington's first-inning single and a walk in each of the next two before the A's grabbed a 1-0 lead on Smith's RBI single in the fourth.
They took advantage of left fielder Cody Ross misplaying Smith's RBI double in the sixth, scored three runs and chased Bard to open a 4-0 edge.
Smith lofted a fly near the corner that Ross overran, and the ball bounced on the track behind him. Kila Ka'aihue followed with a double into the right-field corner and, after Bard hit Kurt Suzuki on the left hand, Brandon Inge had an RBI double. Matt Albers got the next two batters, stranding runners on second and third.
Boston had the first two runners on in the fifth, but Marlon Byrd failed on two sacrifice attempts before popping out. McCarthy then easily retired the next two hitters -- Mike Aviles and Ryan Sweeney.
Byrd's sacrifice fly made it 4-1 in the seventh.
- Middlebrooks drew a four-pitch walk in his first plate appearance, then stole his first base four pitches later. He had an infield hit in his first at-bat. "I was like, 'Man, I wish I got a real hit,' " he said. "The next at-bat went a little better."
- The teams wore 1936 throwback uniforms. That year, the A's -- then in Philadelphia -- sold Jimmie Foxx to the Red Sox. His daughter, Nanci Foxx Canaday, was at the game.
- Oakland 2B Jemile Weeks was out with a strained groin and Melvin felt it would be best to rest him with an off-day on Thursday.
- Boston C Jarrod Saltalamacchia turned 27 on Wednesday.
- Coco Crisp left the game in the eighth inning with an illness.