Kevin Youkilis and Jason Varitek each hit home runs to lift Boston past Tampa Bay 4-2 on Saturday and level their Major League Baseball play-off series.
The reigning World Series champion Red Sox won their second game in a row to deadlock the best-of-seven American League Championship Series at 3-3.
The result forces a seventh-game showdown in Florida on Sunday.
Sunday's winner will face the National League champion Philadelphia Phillies in the best-of-seven World Series.
That starts on Wednesday in the home ballpark of the American League champion.
Tampa Bay's Rays are looking for their first-ever World Series berth while the Red Sox seek their third title in five seasons after an 86-year title drought. The Phillies won their only World Series title in 1980.
The Red Sox, whose rally from a seven-run deficit to win 8-7 Thursday in game five was the second-greatest comeback in play-off history, seized a 3-2 lead on Jason Varitek's solo homer in the sixth inning.
"We went out there and played like it was our last game. It was awesome"
Japan's Hideki Okajima replaced Boston starter Josh Beckett in the sixth and hurled two hit-less innings for the Red Sox before closing relief ace Jonathan Papelbon baffled the Rays in the ninth to complete the victory.
The Red Sox made baseball history in 2004 when they became the first team to win a best-of-seven series after losing the first three games, rallying in the American League finals to defeat the New York Yankees.
Last year, Boston trailed Cleveland 3-1 in the American League finals before rallying to win that series in seven games. They are bidding to do the same again despite seeming all-but doomed in game five last Thursday.
The Rays were seven outs from winning game five.
"The important thing is we found a way to win this game," said Varitek. "It was a big win for us."
Youkilis added: "It's great to get to Game 7, to battle like this. We went out there and played like it was our last game. It was awesome."
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