BOSTON — Shane Victorino was down two strikes, zero balls in the seventh inning when he saw a curveball coming at him.

Victorino straightened it out in a hurry, crushing a grand slam over the left-field wall Saturday night, giving the Boston Red Sox the lead on the way to winning the American League title with a 5-2 win over the Detroit Tigers at Fenway Park.

The Red Sox, who beat the Tigers four games to two, will play in their third World Series in 10 years, starting Wednesday when the St. Louis Cardinals visit Fenway.

Victorino’s blast highlighted an improbable seventh inning that had this team of destiny finding a way after trailing 2-1.

Jonny Gomes, struggling against right-handers, began the seventh with a double against Max Scherzer.

With one out, rookie Xander Bogaerts, the ice water still frigid in his veins, walked on a full count.

Jacoby Ellsbury reached on an error from magical shortstop Jose Iglesias, who could not keep a ground ball in his glove.

Then came Victorino to face reliever Jose Veras. He took a curveball for a strike. He fouled off another curveball.

Then came curve No. 3.

Victorino slammed it, as in really hit it hard. The ball dropped into the first row of the Monster seats and Fenway erupted. Victorino pounded his chest as he rounded first base.

Boston relievers Craig Breslow and Koji Uehara preserved the lead in the eighth and ninth, respectively.

Red Sox starter Clay Buchholz pitched two batters into the sixth inning and did as predicted: strong start and fade at the end.

After five scoreless innings, Buchholz began the sixth by allowing a walk and a single. Both runners scored on Victor Martinez’s single to left off reliever Franklin Morales for a 2-1 Tigers lead.

Buchholz began the game allowing an infield single to Torii Hunter. But he settled down after that, retiring five straight batters, three by strikeout.

He allowed a total of four baserunners in the first five innings, none of whom reached second base.

Scherzer was just as good. He got into a mini-jam in the first on a two-out single to Dustin Pedroia and a walk to David Ortiz. But Mike Napoli grounded out. Scherzer struck out the side in the second.

Bogaerts began the third inning by falling behind 0-2 to Scherzer, but then worked a seven-pitch walk. Ellsbury followed with a full-count walk and the Red Sox were threatening with no outs.

Victorino tried to bunt but popped up to Scherzer, who charged to make a sliding catch.

Pedroia got the Fenway crowd to its feet with a blast that was just left of the left-field foul pole. The umpires reviewed the play and confirmed it was a foul.

Pedroia then grounded to Miguel Cabrera at third for a inning-ending double play.

Scherzer got into a groove. He retired seven straight, and with two outs was ahead of Bogaerts 1-2 in the fifth inning.

But Bogaerts again worked the count full and then smacked a fastball off the Monster in left- center for a double – his third of the postseason. Ellsbury singled to right, scoring Bogaerts, and the Red Sox led 1-0.

Buchholz came out in the sixth inning, to face the top of the order for the third time. That was significant. In two previous playoff games, Buchholz allowed only one run total when facing the order twice. He gave up seven hits after that.

Buchholz walked Hunter and gave up a single to Cabrera.

Manager John Farrell pulled Buchholz and brought in unpredictable lefty Franklin Morales. He walked Prince Fielder to load the bases and gave up Martinez’s two-run single.

Brandon Workman relieved, still with no outs. Jhonny Peralta grounded to Pedroia, who tagged Martinez and threw home. Fielder tried to run back to third but Saltalamacchia ran him down for the double play. Workman struck out Alex Avila to end the inning.

In the seventh, Workman picked off Austin Jackson for the second out. With runners on first and second, Junichi Tazawa relieved and Cabrera grounded out on a diving play from Stephen Drew.

Then came the seventh and a grand slam, and another invitation to the World Series. 

NOTES: Bill Mueller threw out the ceremonial first pitch … The Dropkick Murphys sang the national anthem and then followed it with “Shipping up to Boston,” complete with Irish step dancers …

Kevin Thomas can be reached at 791-6411 or:kthomas@pressherald.comTwitter: ClearTheBases