If the Red Sox found a way to win that one, they'd still have to go up against Justin Verlander in Game 7.
Lester wasn't dominant and didn't go as deep in the game as the Red Sox would have liked, but he was good enough, and he helped himself and his team in the process.
In the end, the Red Sox won, 4-3, and now must only win one of those two games at home to go back to the World Series for the first time in six years.
"Tonight was huge, for obvious reasons," Lester said. "Just obviously putting us up, 3-2, going home."
From the beginning, Game 5 was a grind for the left-hander.
He walked a batter and gave up two singles in the first inning, only to be bailed out when a banged-up Miguel Cabrera was thrown out at home plate on a Jhonny Peralta single to exit the threat unscathed.
Lester gave up a hit and a walk in the fourth, but got a 1-6-3 double play to end that inning.
In the fifth, he gave up two hits, including a Cabrera RBI single, to put Detroit on the board, and in the sixth, he issued a leadoff walk to Victor Martinez and a one-out Omar Infante single that chased him after 98 pitches.
But it would have been worse if not for a small piece of genius, courtesy of Lester and his glove.
With none out and Austin Jackson on first base in the fifth, former Red Sox shortstop Jose Iglesias bunted. Lester hopped off the mound to his left to field the ball, but the ball skirted around the top edge of his glove and fell back to the infield grass, rolling in front of him.
Lester didn't give up, putting his glove down on the grass again and flicking the ball with the webbing to waiting first baseman Mike Napoli. The ball stuck in the heel of Napoli's glove, and Iglesias was out by a step in a play that was sure to be replayed into Friday on the highlight shows.
"Obviously, with Iggy running, you know you don't have much time," Lester said. "For whatever reason, I decided not to open my glove up and let the ball come in and made it a little bit more difficult.
"But just all reaction right there. [I was] fortunate enough with Iggy running down the line hard, getting it to Nap just in time. That was obviously a big out in that inning. Just all reaction … lucky enough to get the guy out."
The bad news from Thursday was that Lester's 5 1/3-inning outing was the shortest start of his postseason career. The southpaw's quickest previous outing was in Game 3 of the 2008 ALCS against Tampa Bay, when he lasted 5 2/3 innings in a game the Red Sox and he lost, 9-1.
The good news on Thursday was that the bad news didn't matter.
Boston's bullpen did the job, preserving Lester's win, and he is now 10-1 with a 2.72 ERA this year (regular season and postseason) in 14 starts following a Red Sox loss.
He's also set up perfectly to start Game 1 of the World Series, should the Red Sox advance. He'd have five days of rest for the Fall Classic, which begins next Wednesday on FOX.
And this: If the Red Sox can win Game 6 or 7, it will start in Boston.
"He's a horse," catcher David Ross said of Lester. "The guy knows what he's doing. He competes his tail off.
"That's what we have in here -- a lot of guys who compete their tails off."