BOSTON - With two swings of Big Papi's powerful bat, the Boston Red Sox went from edgy to euphoric.

Now they feel confident sending pressure-tested David Wells to the mound Friday night against the New York Yankees. The Red Sox have a chance to tie their rivals for the AL East lead in the opener of a season-ending three-game series.

"Everybody knows Boomer's a big-game pitcher and tomorrow's probably as big a regular-season game as you can have," infielder Tony Graffanino said after Thursday night's come-from-behind 5-4 win over Toronto.

David Ortiz was cool in the clutch against the Blue Jays. He tied the game in the eighth with his 47th homer, which tied him with New York's Alex Rodriguez for the AL lead and was his 19th that tied a game or put Boston ahead. Ortiz then won it with a single in the ninth for his major league-high 146th RBI.

His teammates poured from the dugout and mobbed him between first and second.

"The best thing that ever happened to this team was winning this game tonight," Ortiz said. "Everybody was on their toes."

"For what he did tonight, game-tying and game-winning (hits), if that's not enough to win the MVP, I don't know what is," said pitcher Matt Clement, who left with no outs in the sixth and Toronto leading 4-1.

The Butler native had a rough outing in his last regular-season start, giving up eight runs, four hits and three walks.

For the year, Clement is 13-6 in 32 starts with a 4.57 earned run average. He pitched 191 innings, surrendered 192 hits, 97 earned runs, 68 walks and recorded 146 strikeouts.

Ortiz also singled and scored on Manny Ramirez's 42nd homer in the sixth that made it 4-3, and he certainly didn't hurt his chances for the AL MVP award despite his being a designated hitter while Rodriguez, another top contender, is a smooth fielding third baseman.

For the Red Sox, making the playoffs is more important.

They would win the division by sweeping the Yankees, who lead by one game. New York would take it by winning two of the three games.

The Red Sox are tied for the wild-card berth with Cleveland, which finishes with three home games against the AL Central champion Chicago White Sox. If Boston and Cleveland each win two games, they'd finish in a three-way tie with New York.

In that case, Boston would play at New York on Monday to decide the AL East with the loser facing Cleveland on Tuesday for the wild card. That game would be in Boston or New York.

"We just have to focus on tomorrow's game," Kevin Millar said. "Whoever set the schedule this year is a genius."

In 2003, the Red Sox lost the seventh game of the ALCS to the Yankees' on Aaron Boone's 11th-inning homer. Last year, they lost the first three games of the ALCS then beat the Yankees in the last four before sweeping St. Louis for their first World Series championship in 86 years.

"Every year it gets more exciting," Millar said. "It's going to be three Super Bowl games."

In Friday night's opener, rookie Chien-Mien Wang will pitch for New York. He's 8-4 with a 4.02 ERA but lacks the experience of the 42-year-old Wells, who's 14-7 with a 4.47 ERA.

The last two matchups are Randy Johnson (16-8) against Tim Wakefield (16-11) on Saturday and Mike Mussina (13-8) against Curt Schilling (7-8) on Sunday.

Jonathan Papelbon (3-1) was Boston's best pitcher Thursday. The 6-foot-4, 230-pound hard-throwing rookie entered with the score 4-3 and allowed two hits in 2 2-3 scoreless innings.

"I felt very confident," he said after his 16th major league outing. "I'll be ready (for the Yankees). I'll have my game face on."

Ortiz saw a resemblance to a former Red Sox star: "We've got the future Roger Clemens in the house. This kid is something else."

Papelbon even retired Frank Catalanotto, who homered and drove in three runs Thursday and went 9-for-15 in the last three games of the series.

"I see the ball well here," Catalanotto said. "I think the Red Sox have a big advantage this weekend because they have the home field."

Toronto led 1-0 in the second when Eric Hinske hit the first of his three doubles, stole third and scored on catcher Jason Varitek's wild throw. Catalanotto doubled in a run in the third, but Boston made it 2-1 in the bottom of the inning when Graffanino doubled and scored on Edgar Renteria's groundout.

Catalanotto's two-run homer, his eighth of the season, after Russ Adams' double made it 4-1.

"It was nice to get a couple of runs early and quiet their crowd, but when Manny hits his home run, it was `Here they come again,'" Hinske said.

Ortiz tied it with a leadoff homer in the eighth off Vinnie Chulk. Then he won it with his single to left after Johnny Damon singled and stole second before Renteria walked.

That set off a roar of "MVP! MVP!" from the fans, who also chant that when Ortiz comes to the plate.

"That kind of puts you in a good mood," Ortiz said. "You feel like Superman. You feel like I can't let my people down."