The Red Sox won the late game 18-9 after losing the opener 6-5 for their 12th loss in 15 games, trimming their lead over Tampa Bay to 1 1/2 games in the chase for the wild card. The Rays were idle, with a four-game series against the New York Yankees starting Tuesday.
Night game starter John Lackey fell behind 3-0, but the Red Sox took a 4-2 lead after one, made it 6-3 in the second and 11-5 after three innings. Then Lackey gave up another run in the fourth and two more in the fifth before Scott Atchison (1-0) came on for a one-pitch double play to end the inning.
In all, Atchison pitched to three batters and got two double plays, while also dropping a throw covering first for an error.
Orioles starter Brian Matusz (1-8) got just five outs, allowing six runs and six hits.
Boston slugger Adrian Gonzalez reached base seven straight times in the doubleheader, Marco Scutaro had six hits and Dustin Pedroia drove in five runs on the day. Jed Lowrie hit a three-run homer in the nightcap that erased the early deficit and gave the Red Sox the lead for good.
But Lackey still couldn't get through the fifth. He has allowed 25 earned runs in 24 2/3 innings in his last five starts, with three losses and two no decisions.
The Red Sox eliminated any doubt with seven runs in the seventh, the first when Ellsbury hit a long fly ball that bounced off the railing of the Red Sox bullpen wall in right-center and caromed toward left field. Two fielders gave chase, but Ellsbury circled the bases and scored standing up.
The next five batters reached safely before Jackson homered over the Green Monster to make it 18-9.
Jeremy Guthrie (9-17) pitched the last-place Orioles to the win in the day game. Robert Andino and Nolan Reimold hit back-to-back homers into the Green Monster seats off Kyle Weiland (0-3) as the Orioles, who had been outscored 40-20 at Fenway Park this year, won in Boston for the first time in six games.
The Red Sox winnowed a four-run deficit to 6-4 in the fifth inning and appeared to score another, but David Ortiz's liner down the right-field line was ruled foul by first-base umpire Mike Estabrook.
Replays showed it caromed off the lower part of a short wall in fair territory near the Pesky Pole.
"That's the breaks of the game," Pedroia said. "We've played a hundred-something games. We're not going to say the season's over because an umpire missed a call."
Boston, which lost three of four games against Tampa Bay last weekend, led the Rays by nine on Sept 3. The Red Sox have dropped 15 of 20 since they held a 1 1/2-game edge over New York atop the AL East on Aug. 30.
The Red Sox have six games remaining against Baltimore and three in New York against the Yankees. The Rays have 10 to play, seven of them against the Yankees.
Notes
Orioles manager Buck Showalter said he wasn't ready to put INF Mark Reynolds back in the lineup after he missed Sunday's game. Reynolds was hit in the helmet by a pitch on Saturday. … Red Sox manager Terry Francona said OF J.D. Drew may see a doctor soon to check the "stability" of a broken middle finger. Drew has been sidelined since July 20 with a left shoulder injury and broke his finger on a rehab assignment. … The first game was a makeup of a May 17 rainout. … Gonzalez went 0-for-12 in the Tampa Bay series and made outs in his first two at-bats Monday before reaching on a double, four singles and two walks. … Boston's 20 hits and 18 runs in the late game tied season highs. … The Red Sox committed three errors in the late game.