It was the most strikeouts by a Boston left-hander since Bruce Hurst had 14 K's on May 5, 1987.
"He was awesome," said second baseman Dustin Pedroia. "I hope he builds on that and keeps it going. That's some of the best stuff in baseball that he threw out there today."
Of the three hits off Lester, none left the infield. The only time a Toronto hitter reached the outfield all day against Lester was a sacrifice fly by Vernon Wells in the first.
This, on a day Lester improved to 4-5 and lowered his ERA to 5.65. In other words, Lester will need a few more standout performances to get his numbers back to last year's level, when he went 16-6 with a 3.21 ERA.
"You kind of wonder how a guy comes into the game with a 6.00 ERA with the kind of stuff that he has," said Wells. "When he's on, it's difficult. Obviously, when you see the kind of numbers that he put up against us, especially with the strikeouts, it's impressive."
If there had been a constant to Lester's recent struggles, it was that one big inning would haunt him. But there were no big innings in this one, as Lester had overpowering stuff. He also mixed it up, throwing his share of dazzling curveballs and roughly 20 changeups, a pitch Lester integrated into his repertoire in Spring Training.
"That's been a focus of mine this year and obviously the past couple of starts -- just shut-down innings," Lester said. "Especially after we score. And I haven't been able to do a very good job of that this year. I was able to get in a little bit of a rhythm after the first inning and do a little better job of that."
The Boston offense, which had scored three runs or fewer in the previous five games, supported Lester's cause.
Manager Terry Francona switched up the lineup, moving Pedroia to the leadoff spot, sliding Jacoby Ellsbury to eighth and boosting J.D. Drew from third to second.
Coincidence or not, Pedroia responded by belting a three-run homer to snap a 1-1 tie in the fourth. It was Pedroia's first long ball since his solo shot in his first at-bat of the season.
"I'm not trying to hit home runs, but they happen," said Pedroia, whose homerless drought ended at 190 at-bats. "It was kind of just a line drive that snuck out. The only thing I'm trying to do is have good at-bats. We were fortunate enough to sneak one out and get three runs out of it."
Kevin Youkilis, batting third for the third time this season, also seemed to benefit from his new slot, belting a pair of solo shots, including one in the top of the first that got the day off to a promising start.
The Red Sox had four homers on the day, as Jason Bay smashed No. 15.
But it was in that fourth inning that the tide shifted, as the Red Sox mixed it up offensively.
David Ortiz, who has spent the season in a deep slump, led off that fourth with a double off the wall in center. Jason Varitek followed with a walk. Then Jacoby Ellsbury produced Boston's first sacrifice bunt of the season, putting runners at second and third with one out.
After Nick Green struck out, Pedroia lined one down the line in left, just clearing the wall.
"It was a good day," said Varitek. "Youk starts with the homer, and then we have the big inning when David leads us off with the double. Nice to see one finally fall for David. That was a big inning for us, and that was a big double to get us started. It allowed me to work the walk, Jacoby bunts us over and we get the three-run homer from Dustin."
Mike Lowell bumped the lead to 5-1 in the fifth with a two-out RBI double to left.
The Red Sox put it away with three more in the eighth. Green doubled, moved to second on Pedroia's sacrifice bunt and came in to score on Drew's sac fly to center. Youkilis then launched his second solo shot of the game on a line drive over the left-field wall, Bay followed with a solo shot of his own to left.
The Red Sox, who open a three-game series at Detroit on Tuesday night, are 3-4 on this 10-game road trip.
"It started with Lester," said Francona. "He was powerful. Shoot, the three hits were two bouncers to short and the ball to Mikey Lowell that would have been a great play at third. He threw strikes, he missed bats. They fouled off a lot of pitches, drove his pitch count up. He was good. He used all his pitches, and there was power behind them."
The punchouts didn't excite Lester nearly as much as the win.
"Strikeouts don't really matter," Lester said. "I would have liked to have gone a lot deeper in the game, but I threw the ball well. I've been feeling pretty well. Just one pitch last start cost me the game. I feel like I'm going in the right direction."
And if Lester stays in the upward swing, the Red Sox might well follow suit.
"When he pitches like that, I hope we win them all," Ellsbury said. "If he throws like that, I like the rest of the season going forward."