Shane Victorino belted a seventh-inning grand slam homer to put the Boston Red Sox into the World Series with a 5-2 victory over last year's beaten team, the Detroit Tigers.
Victorino's blast turned a 2-1 deficit into a three-run lead that ended up clinching the American League Championship series, as the Hawaiian thumped his chest and roared in delight while rounding the bases.
The Red Sox, who won the best-of-seven series 4-2, will meet the National League champion St Louis Cardinals for Major League Baseball's championship starting on Wednesday back at Fenway Park in Boston.
The showdown will be a rematch of the 2004 Fall Classic, won by Boston in a four-game sweep that ended their 86-year championship drought.
Red Sox closer Koji Uehara was named Most Valuable Player of the series after registering one win and three saves in Boston's turnaround triumph. The Red Sox had finished last in the AL East in 2012 with a 69-93 record.
"From day one in spring training there was something special about this team," said Victorino, one of several players brought in to change the chemistry.
"Guys came here in one mindset. I know the last couple of years have been tough here. But you know, we put that all behind us. Boston strong."
A tense pitching duel between Boston's Clay Buchholz and Detroit's Max Scherzer turned into a see-saw struggle as the Red Sox scored in the fifth to take a 1-0 lead, only for the Tigers to take it right back in the sixth, moving 2-1 ahead.
The seventh belonged to Boston as Victorino, who had been a dismal 2-for-23 at the plate in the series, connected off reliever Jose Veras's third successive curve ball with bases loaded for the game-winning hit over the fence in left.
It was the second grand slam for Boston in the series following an eighth-inning roundtripper by David Ortiz in game two that erased a 5-1 deficit and helped the Red Sox win 6-5.
Uehara, who pitched seven scoreless innings in relief and struck out 11 in the series, registered the final out with a strikeout of Jose Iglesias and jumped into the arms of catcher Jarrod Saltalamacchia as the celebrations began in Boston.
The Tigers were left to wonder 'what if?', as they squandered an opportunity to score more runs in the sixth and opened the door to Boston's winning rally in the seventh.
After Victor Martinez drove in two runs with a bases-loaded single off the 'Green Monster' wall in left, Detroit still had men on first and third with none out but suffered a baserunning blunder by Prince Fielder.
Boston reliever Brandon Workman replaced Franklin Morales and got Jhonny Peralta to bounce to second baseman Dustin Pedroia.
Pedroia tagged Martinez out, and with Fielder caught in no-man's land between home and third, fired home in time for catcher Saltalamacchia to chase Fielder back toward third and tag him out.
In the seventh, Boston's Jonny Gomes led off with a laser drive off the top of the Green Monster that went for a double.
Scherzer then walked Xander Bogaerts to put men on first and second, and was removed from the game.
Jacoby Ellsbury then hit a grounder up the middle that shortstop Iglesias reached but bobbled for an error that loaded the bases and set the stage for Victorino.
"We made a couple of mistakes and they capitalised on them," said Tigers' rightfielder Torii Hunter, a 17-year veteran who has still to reach his first World Series.
"Victorino got the big hit, the grand slam, and we couldn't do anything about it. They played well."