Lester (9-12) gave up three runs and four hits in seven innings as the Red Sox failed to get their first three-game winning streak since posting four consecutive victories July 28-31.
"I've got to keep looking at those positives and just keep plugging away," Lester said. "Just keep working those things and try to pitch as many innings as I can every time I take the ball."
The game was scoreless until the bottom of the seventh, when Yan Gomes grounded a two-out single up the middle, just the second hit allowed by Lester.
Rajai Davis came on as a pinch runner and stole second, then scored on Vizquel's single to center. The hit was Vizquel's 2,872nd, matching him with Jesse Burkett for 42nd on the all-time list and leaving him just one behind Hall of Fame slugger Babe Ruth.
"Not even in my wildest dreams was I going to think that you can bring the name of Babe Ruth next to mine," Vizquel said.
Blue Jays manager John Farrell said he'll likely give Vizquel a chance to match Ruth's record when Toronto begins a three-game series at Yankee Stadium on Tuesday.
"I'd be crazy not to," Farrell said. "For him to tie if possible in New York will be very fitting."
Red Sox Bobby Valentine said Vizquel's hit came on Lester's only poor pitch.
"I don't know if he threw a bad pitch except for maybe the curveball to Vizquel," Valentine said. "The whole game he was in and out, doing a heck of a job."
Lester acknowledged that he was "trying to be quick to the plate" with the speedy Davis running the bases.
"As we've seen many times before, when Rajai gets on the bases he can make a lot of things happen," Farrell said.
Hechavarria hammered Lester's very next offering, a cut fastball, hooking it around the foul screen into the second deck in left for his second career home run.
"I thought that cutter was a pretty good pitch," Valentine said. "Not many guys keep that fair in the air."
Toronto pulled away with two more in the eighth off Daniel Bard. Brett Lawrie led off with a double and scored on Colby Rasmus' single to left, with Rasmus taking second on Ryan Kalish's error. Rasmus scored two batters later on Moises Sierra's RBI single off Scott Atchison.
Lester set down the first six batters in order before Vizquel doubled to begin the third, but the Blue Jays didn't get another base runner until Sierra's leadoff walk in the fifth. Sierra was safe at second when Lester threw high to second on Gomes' sacrifice bunt, then had to scamper back to the bag after nearly getting caught in a rundown.
Toronto failed to capitalize when Lester struck out Vizquel and Hechavarria, then got Anthony Gose to ground into a fielder's choice.
Boston put a runner in scoring position three times in the first four innings against Blue Jays right-hander Brandon Morrow but failed to score. The Red Sox stranded men at first and second in the first, left a runner at second in the second and stranded runners at first and second again in the fourth.
"We fired a lot of blanks with men on base today," Valentine said.
Ciriaco had a two-out single off Lyon in the seventh and stole second while Jose Iglesias was batting. When the count got to 2-2 on Iglesias, Valentine brought Daniel Nava on as a pinch hitter. Nava grounded back to the mound on the first pitch.
"Just trying to get a run for Jon, obviously," Valentine said. "Told Daniel if (Ciriaco) steals second, you've got it."
The Red Sox put runners at first and second with one out in the eighth but Ross grounded into a double play.
Morrow gave up four hits in six scoreless innings. He walked one and struck out three.
Toronto DH Edwin Encarnacion (sore right big toe) was scratched from the lineup, along with SS Yunel Escobar (illness) and C Jeff Mathis (flulike symptoms). ... Valentine insisted he wasn't trying to be critical when he said Friday that his struggling Red Sox had "the weakest roster we've ever had in September in the history of baseball." On Sunday, Valentine called his earlier comments "a statement of fact because of the injuries and our Triple-A team in the playoffs." ... The Red Sox have not been caught stealing since Aug. 29, swiping 16 straight bases in that time.