And still the left-hander delivered another victory over the Baltimore Orioles.
J.D. Drew also homered for the Red Sox, who trailed 5-2 before rallying to end a three-game skid. Boston remains eight games behind AL East-leader New York and trails second-place Tampa Bay by seven games.
"We need to chip away and get some wins," Lester said. "It was big that we could come back tonight."
Lester's latest victory against the Orioles was anything but typical. He came in with a 2.00 career ERA against the Orioles and was 2-0 with an 0.47 ERA in his three starts this year.
Lester yielded more runs (five) in the first two innings than in any of his previous 15 outings against Baltimore.
"Usually this mound is one of my favorite places to pitch. For some reason it felt like a rainstorm had come through," he said. "It was wet and I had clumps on the bottom of my shoe and was slipping a little bit."
Fortunately, Lester recovered in time to give Boston a chance to make up the deficit.
"I think once he started to settle in and really pitch, he was able to drop all his off-speed pitches in there for strikes," Baltimore's Ty Wigginton said. "When you're facing a pitcher like Lester and he's able to throw four pitches for a strike, it gets tough."
Beginning with the last out in the second inning, Lester retired 11 straight -- seven by strikeouts.
"It's a testament to him, keeping the club in the game and not giving in," Baltimore manager Buck Showalter said.
Lester (15-8) allowed five runs and eight hits in six innings. He struck out 10, walked two, hit a batter and threw a wild pitch.
"Early on, I really didn't have a feel for what was going on. I don't really know how to explain it," Lester said.
When he walked off the mound for the last time, Boston trailed 5-3. Lester then watched in the dugout as the Red Sox batted around in the seventh.
Jonathan Papelbon worked the ninth for his 34th save.
Adam Jones had two RBIs and Julio Lugo scored twice for the Orioles, whose four-game winning streak ended. Baltimore fell to 17-11 under Showalter, who will have to wait at least another day to become the 64th manager in big league history to reach 900 wins.
Boston went up 1-0 in the first inning when Scutaro got an infield hit and scored on a two-out double by Ortiz, who reached the 80-RBI mark for an eighth consecutive season.
Baltimore responded with four runs on four hits in the bottom half, an uprising fueled by Lester's lack of command. After Lester hit Wigginton with a pitch to load the bases, Jones hit a two-run double. Wigginton then scored on a wild pitch and Felix Pie hit an RBI double off the right-field wall.
"The first inning was a tough one," Boston manager Terry Francona said. "When you're already warming up [reliever Robert] Manuel in the first inning, that's not an easy way to win."
The Red Sox got a run back in the second when Ryan Kalish broke a 3-for-29 slump with an RBI double. The Orioles made it 5-2 in the bottom half when Wigginton drove in a run with a two-out single.
"You score five runs off Lester, of course we'd take that," said Baltimore's Nolan Reimold, who went 1-for-3 with a sacrifice fly. "But it's a longer game than two innings. so you want to keep adding on as many as you can. We kind of fizzled a bit out there after the second inning and they ended up adding some runs at the end."
Drew launched the comeback by snapping an 0-for-14 skid in the fifth with his 18th homer. Game notes
The game was delayed in the ninth when home plate umpire Tom Hallion was struck by a foul ball. ... Jones left with upper back soreness. ... Reimold, one of the Orioles' three callups on Wednesday, got his first hit in the majors since May 11. ... Lester reached double-digits in strikeouts for the fifth time this season and 12th time of his career. ... Every Boston starter had at least one hit.