Lester walked three straight after getting the first out in the seventh, but reliever Daniel Bard got a pair of popouts to end a bases-loaded threat.
"It's great. He bailed me out," Lester said. "He's done that all year for us, and hopefully, he can continue to do it. You obviously see what he brings to the table every night he pitches. He's done great, and I can't speak highly enough about what he's done coming out of the bullpen for us."
Though Lester got some help from Bard -- who was throwing 99-mph fastballs followed by 91-mph changeups -- the big boost came from the bat of Kevin Youkilis. Starting at third base for the first time this season, Youkilis finished 3-for-5 with two doubles, a home run and three RBIs. His 378-foot homer on the first pitch he saw from Jeremy Guthrie to lead off the seventh broke a scoreless tie.
"He's a good hitter," manager Terry Francona said matter-of-factly. "He takes his walks, swings at strikes and never gives at-bats away. He's dangerous. He's a good player all the way around."
Guthrie, who retired 15 straight at one point, conceded that he didn't elevate the pitch and that Youkilis made a good swing on it.
"[Guthrie's] good; he drops down a little bit," Youkilis said. "He pitched well. We're very fortunate to get out with a win by grinding out at-bats."
The Red Sox almost got to Guthrie sooner.
With one out in the sixth, Marco Scutaro yanked a Guthrie offering down the left-field line. It was ruled foul, and after an argument from Francona, the umpires went into the tunnel behind home plate for the first review of 2010 at Oriole Park at Camden Yards -- the third overall in Baltimore. The call stood, and the pitchers' duel was still intact. Guthrie struck out Scutaro before Dustin Pedroia singled to end the streak of outs.
Fortunately for Boston, opportunities continued to arise. And the offense came through when needed, going 5-for-11 with runners in scoring position.
With one out and the bases loaded in the ninth, former Baltimore farmhand Darnell McDonald looped a double to left to score a pair of runs. Bill Hall then doubled to score two more and chase reliever Will Ohman. Jason Berken came on and didn't fare much better, walking two and allowing a double to Youkilis before striking out Victor Martinez. When the smoke cleared, the Red Sox had six more runs and a commanding eight-run advantage.
In hindsight, Boston was fortunate to have put up the big inning, as reliever Joe Nelson struggled to close out the Orioles.
Baltimore put up the first runs since Juan Samuel was named interim manager when Scott Moore singled home a pair with one out in the ninth. Ramon Ramirez came on to bail out Nelson, getting a grounder and a popup to end it.
The Orioles weren't starved for opportunities, having left nine runners on base, going 1-for-9 with runners in scoring position.
After Youkilis' 12th homer of the year, the Orioles tried to rally in the bottom of the seventh, loading the bases with one out as Lester walked three straight before exiting. Bard entered and got pinch-hitter Luke Scott and Corey Patterson both to pop out.
Center fielder Josh Reddick, recalled before the game, tripled to lead off the eighth. After a Hall groundout to short, Scutaro chopped a grounder over the left side of the drawn-in infield, scoring Reddick for a two-run lead.
"[Reddick] reached out on an off-speed pitch and showed what kind of hands he has, then he showed his legs," Francona said. "He contributed to our win. That's what we're looking for."
Guthrie departed having allowed two runs on five hits and one walk in 7 1/3 innings. David Hernandez entered and walked Pedroia before inducing an inning-ending double play from David Ortiz.
The game was moving at a brisk pace until the eighth, when all rhythm hit a wall and the Red Sox took advantage, improving to 14-4 in the last 18 games.
"They have swung the bats very well lately," Guthrie said. "They are always a tough team, so to be in a game against a tough pitcher and a tough lineup is a real positive."