BOSTON (AP) -The Boston Red Sox offense overcame its season-long struggles in a big way on Friday night.

The Red Sox rallied from a seven-run deficit, sparked by home runs by Jason Bay and J.D. Drew, to defeat the Baltimore Orioles 10-8.

''We have the ability to have two or three guys not on their games and still score a lot of runs,'' said Bay, who broke an 8-8 tie with a sacrifice fly off Danys Baez (0-1) in the eighth inning to score Dustin Pedroia .

Bay was 1-for-3 with three RBIs, Drew was 2-for-2 with three runs scored and Pedroia was 3-for-4 with a double.

''He's a huge part of our offense,'' Bay said of Drew. ''He's an on-base machine when he's going well.

''I don't think it's a huge coincidence he gets on, Petey (Pedroia) gets a couple of hits and we score a bunch of runs.''

The Orioles raced out to a 7-0 lead in the second inning, keyed by Nick Markakis ' grand slam, and chased Brad Penny , making his first start at Fenway for the Red Sox , in the third.

The Red Sox rallied for four runs in the bottom of the inning. Drew walked and Bay homered into the Orioles' bullpen off Orioles starter Jeremy Guthrie . The Red Sox added two more runs in the inning on an RBI single by Jacoby Ellsbury and David Ortiz 's sacrifice fly.

Manny Delcarmen was the first of five relievers to combine for six scoreless innings, allowing only an RBI double to Markakis - the run was charged to Penny - in the fourth. He gave way to Javier Lopez in the sixth.

''Their bullpen did a tremendous job,'' Orioles manager Dave Trembley said. ''Their bullpen did a great job coming in and getting big outs in key situations. That was the difference in the game.''

Drew homered to lead off the third, cutting it to 7-5.

''I was just trying to get a pitch I could handle and they were throwing too many pitches out of the zone. I got a couple of pitches out over the plate I could hit and finally put a swing on the ball they couldn't catch,'' Drew said.

Markakis made it 8-5 with an RBI double in the fourth.

But Drew keyed the Red Sox again, this time with a two-out triple in the fifth. Guthrie walked Bay and Lowell to load the bases.

''He took some really good swings,'' Red Sox manager Terry Francona said. ''He got some pitches he could handle, didn't chase out of the zone and then hit him with authority.''

Aubrey Huff then committed an error on a grounder by Jason Varitek , as Drew scored Boston's sixth run. Nick Green followed with a two-run double, tying the game 8-8.

''It's a play you've got to make,'' Huff said. ''I take full credit for that one.''

The Orioles threatened in the eighth. Ramon Ramirez allowed singles to Brian Roberts and Adam Jones . Hideki Okajima relieved and got Markakis to fly out, moving both runners into scoring position. But Okajima struck out Huff swinging to end the inning.

Ramirez (1-0), acquired in the offseason for Coco Crisp , relieved Lopez in the sixth and earned his first win with the Red Sox .

Jonathan Papelbon pitched the ninth for his third save.

Markakis was 2-for 4 with five RBIs, including a grand slam.

Penny allowed the first four batters in the second to reach base, including a four-pitch walk to Ryan Freel , which gave the Orioles a 1-0 lead. Penny retired Cesar Izturis , but Roberts singled and Jones walked on four pitches to give the Orioles a 3-0 lead.

Markakis then hit the second pitch from Penny over the center-field wall, giving the Orioles a 7-0 lead. It was his second homer of the season and the second grand slam of his career, the other was against Kansas City on April 13, 2007.

The seven runs were the most scored in an inning this season by the Orioles and the most allowed by the Red Sox .

Notes: Bay earned his 500th career RBI on his second-inning homer. ... Pumpsie Green threw out the first pitch. The Red Sox honored the former infielder on the occasion of the 50th anniversary of his breaking the color barrier for the team in 1959. ... Roberts, who started the season 6-for-6 with runners in scoring position, including his base hit in the second, had his streak snapped when he grounded out to Kevin Youkilis in the third inning. ... Izturis is 0-for-16 in the first four games of a seven-game trip. ... Youkilis and Bay have both reached safely in all 10 of Boston's games. ... The Orioles have lost all four of Guthrie's career starts at Fenway.