BOSTON -- David Ortiz was the AL's top batter in the month of May, hitting 10 homers and raising his batting average from .143 to .272.
And yet the Oakland Athletics still needed convincing.
The A's pitched to Ortiz with first base open in the fifth inning, and he launched a two-run, go-ahead homer down the right-field line that sent the Boston Red Sox to a 6-4 victory Wednesday night.
His next time up, the A's granted Ortiz his first intentional walk of the season.
Big Papi is back.
"It's been good to see," Red Sox manager Terry Francona said. "He's swinging the bat great."
Ortiz went 2 for 2 with two extra-base hits and two walks, and Daisuke Matsuzaka settled down after giving up three runs in the first inning as Boston rallied for the second straight game.
One night after scoring nine straight runs to back John Lackey and overcome a 4-0 deficit, the Red Sox scored six in a row after falling behind 3-0. Kevin Youkilis had a two-run single in the first inning, then Ortiz made it 4-3 in the fifth with the drive down the right-field line.
"They're the type of pitchers that you have to get on them early," A's catcher Kurt Suzuki said. "Once they get into a groove, they're pretty darn good."
Matsuzaka (4-2) allowed 10 hits and walked none, striking out seven. He gave up consecutive doubles to Daric Barton and Ryan Sweeney before Suzuki's two-run homer in the first gave Oakland a 3-0 lead.
After his shaky start, though, Matsuzaka did not allow a runner to reach third base until the seventh.
"My only thought was to dig in and keep battling," Matsuzaka said. "Things turned around."
In the seventh, Matsuzaka hit Barton with two outs and Sweeney singled up the middle on a 3-2 pitch. Daniel Bard came in and struck Suzuki out to protect the 4-3 lead, then retired the side in the eighth before Jonathan Papelbon earned his 13th save despite pinch-hitter Kevin Kouzmanoff's homer that made it 6-4.
Ben Sheets (2-4) allowed four runs, seven hits and a walk, striking out one to suffer his first loss in a month and end a string of four no-decisions.
Ortiz hit .363 with 10 homers and 27 RBIs in May to earn AL player of the month honors -- the fourth time he has been so honored, but the first since September 2007. He also doubled and scored in the first inning, and in the seventh he was intentionally walked -- a sure sign that opponents believe his slump is over.
Matsuzaka continued his inconsistent ways.
He took a no-hitter into the eighth inning two starts ago, and in his last outing he matched his career high with eight walks and didn't make it out of the fifth in a 4-3 loss to Kansas City. He showed both forms Wednesday, allowing three runs and four hits in the first inning and then putting up five straight zeros.
"At the beginning, it was almost too many strikes. If that's a problem, we'll take it," Francona said. "He gathered himself up in a hurry and pitched well.
Boston's J.D. Drew hit his first triple since September. ... Sweeney was 1 for 11 against Matsuzaka before getting two hits against him on Wednesday night. ... Jon Lester was named the AL pitcher of the month, his third such honor. ... Francona said former ace Josh Beckett won't throw for 10 days as he tries to recover from a lower back strain. ... Red Sox C Victor Martinez, who had four doubles and five hits Tuesday, was rested with a sore left big toe. He is scheduled to catch Tim Wakefield on Thursday.