The defending World Series champions pulled off the major leagues’ biggest postseason comeback in 79 years, beating the Rays 8-7 Thursday night on J.D. Drew’s two-out single in the ninth to stave off elimination in the American League Championship Series and head to Tampa Bay trailing three games to two.

“It’s tough, but I think this team has battled all year,” Drew said. “We’re in a situation, seven runs down, we know we can make that up if we get going.”

Boston trailed 7-0 with two outs in the seventh, then rallied when David Ortiz’s three-run homer followed Dustin Pedroia’s RBI single. Drew hit a two-run homer in the eighth and Coco Crisp tied it with a two-out RBI single.

Then in the ninth, Kevin Youkilis grounded to Evan Longoria with two outs, and wound up at second when the throw bounced in front of first baseman Carlos Pena. Youkilis was given an infield hit, and the rookie third baseman his third error of the series.

Jason Bay was intentionally walked and Drew lined a single to right to score the game-winner.

“We’re going to go back to Tampa and try to fight back,” Ortiz said.

The series resumes Saturday night at Tampa Bay. The winner faces Philadelphia in the World Series starting Wednesday night.

The seven-run deficit was the largest overcome in a postseason game since Game 4 of the 1929 World Series, according to the Elias Sports Bureau. In that one, the Philadelphia Athletics trailed by eight before a 10-run seventh inning powered them past the Chicago Cubs 10-8.

Tampa Bay starter Scott Kazmir allowed two hits through six innings before being lifted to start the seventh. Kazmir had been moved up in the rotation. Rays manager Joe Maddon pushed top starter James Shields, better at home, back to a potential Game 6 on Saturday night in St. Petersburg. Kazmir has performed better on the road than at home.