"It started with Lester," Red Sox manager Terry Francona said. "He was powerful."
Lester (4-5) allowed one run, three hits and three walks in six innings, lowering his ERA to 5.65. His 12 strikeouts were the most by a Red Sox pitcher this season and the most by a Boston left-hander since Bruce Hurst struck out 14 against Oakland on May 5, 1987.
"He could have beat anybody with the stuff he had today," Blue Jays manager Cito Gaston said.
Lester, who threw 115 pitches, said his only regret was not being able to go deeper in the game.
"I had a pretty good feel for my curveball today and threw a lot of change-ups," Lester said. "That's big with this team. You've just got to keep a good mix and you can't let them look for one area or sit on a fastball. When I did get behind, I was able to have enough soft stuff in the mix where they couldn't just gear up for a fastball."
Jason Bay also homered for the Red Sox, who tweaked their lineup to shake themselves out of a recent offensive slump. Nine of Boston's 11 hits were for extra-bases.
Batting leadoff for the first time this season, Pedroia homered off the left-field foul screen in the fourth inning, his second.
Pedroia was bumped up and outfielder Jacoby Ellsbury dropped to eighth as Francona tried to boost the offense after watching his team score just 13 runs in its previous five games.
"We need to have our on- base guys [up high] for the guys in the middle of the order," Francona said. "It's important."
The moves paid off as every Boston starter except Jason Varitek had at least one hit, helping the Red Sox score more than three runs for just the second time in seven games and improve to 3-4 on their current 10-game trip.
"We scored early and then we added on," Francona said. "That's always a good way to play. We haven't done that very much lately but it was a very good day today."
Francona wasn't sure whether he'd keep the same lineup when the Red Sox open a three-game series in Detroit on Tuesday night. As for Pedroia, the reigning AL MVP isn't concerned about where he hits.
"It doesn't really change my approach," Pedroia said. "Whatever they tell us to do, we're willing to do it. I don't get paid to make the lineup."
Youkilis hit a solo homer in the first off Toronto left-hander Ricky Romero, then hit another solo drive in the eighth off right-hander Brian Wolfe, the sixth multihomer game of his career. Bay followed Youkilis' second drive with an almost identical shot into the left-field bullpen, his 15th.
Trailing 1-0 on Youkilis' first homer, Toronto tied it in the bottom of the first on a sacrifice fly from Vernon Wells.
Pedroia put Boston ahead to stay with his two-out homer in the fourth. The homer was Pedroia's first since he went deep on his first at bat of the season, April 7 against Tampa Bay, a span of 190 at bats.
Toronto's Alex Rios hit a solo homer to left off Masterson in the eighth.
Making his second start since coming off the disabled list with a strained right oblique, Toronto left-hander Ricky Romero (2-2) allowed five runs and six hits in four-plus innings. He walked five and struck out five.
Boston's David Ortiz snapped an 0 for 12 streak with a double to center in the fourth and finished 1 for 5 with a strike out. Ortiz is batting .185.
Lester's previous high in strikeouts was 10, set twice previously. ... Toronto's Aaron Hill went 0 for 3 with a walk, ending his hitting streak at 13 games. ... Ellsbury had a sacrifice bunt in the fourth, Boston's first of the season. The Red Sox were the last team in the majors without a sacrifice bunt. ... The win was Francona's 499th as Boston manager. ... Francona said there's a "decent chance" that OF Mark Kotsay (back) could be activated off the 15-day disabled list before Tuesday's game at Detroit.