BOSTON -- It was only a matter of time before the Red Sox's offense came to life. Unfortunately for the A's, the surge came just before they left Boston.

Mere hours after a report surfaced linking him to a 2003 list of players who tested positive for performance-enhancing drugs, Boston slugger David Ortiz responded to those allegations by touching up reliever Craig Breslow for a momentum-changing three-run home run in the seventh, sending Oakland to an 8-5 loss in the finale of a four-game set.

Rajai Davis and Tommy Everidge had two RBIs apiece for the A's, who received a three-hit effort from Nomar Garciaparra in what was likely his final game at Fenway Park.

"It was nice to get a few hits," said Garciaparra, who was an iconic figure in Boston from 1996-2004. "It also would have been nice to have a victory. That's all I've ever cared about.

"If it was my last game, I'll take it. I still can't believe that unbelievable ovation I got when we came here a few weeks ago. It's special the way I've been treated every time I come up to the plate, and throughout the city. Hopefully, the fans saw in me just how much I appreciated their support. This will always be a big part of my life, and my heart."

Jason Varitek put the Red Sox on the board with a second-inning RBI single, which held up for starter Jon Lester before an Oakland uprising in the sixth.

Everidge delivered Orlando Cabrera on a sacrifice fly to right. Bobby Crosby followed by scoring Garciaparra with a well-struck double to left, and a bloop single from Davis that fell in shallow center plated two more.

But back came Boston in the bottom of the inning, as Mike Lowell chased A's starter Gio Gonzalez with a ground-rule double to right. Varitek then ripped a 95-mph fastball from Russ Springer through the right side, and the Red Sox had trimmed Oakland's advantage to 4-3.

Coming off a strong outing at Yankee Stadium in which he yielded one run on two hits over 6 2/3 innings, the 23-year-old Gonzalez tied a career high by fanning eight Red Sox. The southpaw allowed three runs in 5 1/3 frames.

"He pitched pretty well," A's manager Bob Geren said. "I actually liked what he did. We tried to simplify the game plan, just pump strikes and let his ball have some movement and not get too fine on the corners. It works for him. That's exactly what he needs to do."

Everidge stretched the A's lead back to two runs with a seventh-inning RBI single, but Ortiz put Boston on top for good with one swing in the bottom half of the frame.

After Dustin Pedroia grounded into a double play against Michael Wuertz, a fly ball off the bat of Kevin Youkilis was misplayed by right fielder Jack Cust, who was blinded by the sun.

Jason Bay followed with a walk, and Ortiz greeted Breslow by launching a pitch to his liking into the center-field bleachers.

"We had a bad break there with the ball in the sun," Geren said. "It was tough, but we didn't help things by walking the next guy, and obviously Ortiz hit a fairly decent pitch. He pulled his hands back and hit it a long way. Good at-bat by him, that's for sure."

"I hope he's doing all right," Garciaparra said in reference to the accusations brought against his former teammate. "He did all right today."

The Red Sox added a pair of insurance runs in the eighth, dooming the A's chances of a comeback bid. Down to its final three outs, Oakland could not break through against closer Jonathan Papelbon, despite having the tying run on deck.

Though his club earned a well-deserved split in Boston, Geren lamented the A's inability to cash in on an opportunity to take the series.

"Coming in here and winning two out of four against that team is never a bad thing, obviously," Geren said. "But when you're up two games to one, and you're up in the fourth game, you'd sure like to close it out."