BOSTON - Last week in Miami, the Marlins beat the Red Sox in the first of six inter-league games to be played between the teams in 11 days.

Wednesday night in Boston, the Sox beat Miami for the fourth straight time since, hammering the slumping Marlins 15-5.

David Ortiz, hitting his third home run in as many games (No. 19 on the season), drilled a grand slam during a six-run fourth inning and lefty Felix Doubront earned his eighth win as the Sox won their fourth game in a row overall to escape the American League East cellar.

The win moved Boston two games over .500, the fourth time this season the Red Sox, who surpassed their season high in runs, have been two games over. They have failed in their three previous tries to get to three over and will try again Thursday night against Miami.

The Marlins have lost 12 of their last 14 games.

Mike Aviles hit a three-run homer in the second inning and Jarrod Saltalamacchia hit his 13th, two batters after Ortiz, who is now 9-for-18 with four homers and 11 RBIs during a six-game hitting streak, hit the slam off rookie Chris Hatcher. Hatcher had relieved loser Ricky Nolasco, pelted as he fell to 6-6. Nolasco came in 4-1 in six road starts.

Rookie Will Middlebrooks, who didn't start, hit his seventh homer of the season to cap the scoring in the eighth, the Sox' 16th hit of the game.

Doubront, winning for the fourth time in his last five starts, moved to 8-3 with six innings of work.

Daniel Nava, who missed eight straight starts with a sore hand, went 4-for-5 in his return to the lineup.

Logan Morrison hit his second homer in as many nights, his third against the Red Sox, and John Buck also connected for Miami. Omar Infante, 3-for-30 in the last seven games coming in, had three hits.

Buck appeared to pull a muscle getting out of the batters box in the seventh. He stayed in the game but left for a pinch hitter during his ninth-inning at-bat.

The Marlins opened both the first and second innings with two straight hits and scored a run in each frame.

Jose Reyes and Hanley Ramirez opened the first with single and Reyes scored from first on Giancarlo Stanton's ball double play grounder. Justin Ruggiano opened the second with a double, took third on a bunt single by Omar Infante and scored on Gaby Sanchez's slow rollout to third base (Sanchez also had an RBI single in the fourth, scoring Ruggiano, who tripled).

There were two out and nobody on in the Red Sox second when Saltalamacchia and Kevin Youkilis singled and Aviles hit the first pitch for his ninth homer of the season. Cody Ross, a former Marlin, then cleared the bases with his Fenway wall-ball double to make it 6-2 in the third.

Morrison's second homer in as many nights, his third in the five games against Boston, keyed a two-run Miami fourth that made it 6-4, but an RBI infield hit by Ryan Kalish and the homers by Ortiz and Saltalamacchia broke it wide open. A bases-loaded wild pitch made it 13-4 in the fifth.

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NOTES: Red Sox second baseman Dustin Pedroia, who left Tuesday night's game after re-aggravating his right thumb injury, was held out of the lineup but wanted to play, manager Bobby Valentine saying Pedroia suffered "more a scare" than serious re-injury Tuesday night. "Dustin, in true Dustin fashion, said he didn't want to let his teammates down and wanted to play tonight but [we're] going to give it a day to make sure that it settles in and just make sure we know what we're dealing with, Valentine said." ... Marlins manager Ozzie Guillen on his slumping lineup: "I'm going to stick with the guys. I'm going to believe in them. I'm going to make the same lineup if I can to make sure they know I'm behind them. We know we're not performing. It's not a secret for anybody on this ballclub. I think everybody that wears this uniform knows we're not performing." ... Shortstop Deven Marrero, the Sox' first pick (24th overall) in the recent draft, signed and worked out before the game. ... Temperatures are supposed to remain in the high 90s for Thursday night's series finale, with Miami's Carlos Zambrano (4-5) facing Daisuke Matsuzaka (0-2).