Chris Davis hit a two-run homer and drove in three runs, pacing Baltimore's 6-3 victory over Boston in the finale of a four-game series from Camden Yards.
Nick Markakis finished 4-for-5 with two doubles and scored three times for the Orioles, who won three of four in the set. Adam Jones contributed two doubles and an RBI, with J.J. Hardy and Manny Machado knocking in a run each.
Miguel Gonzalez (5-2) allowed three runs on five hits in 6 1/3 innings, Brian Matusz and Tommy Hunter added 1 2/3 scoreless frames and Jim Johnson tossed a perfect ninth for his 25th save of the season.
"It was fun to watch our hitters hit, especially against Lester," Gonzalez said. "He's been doing a great job this year and always pitched well against us."
Will Middlebrooks clubbed a three-run home run and Jacoby Ellsbury added two hits for the Red Sox, losers in four of their last six.
Jon Lester (6-4) was tagged in defeat for nine hits and five runs over five full frames. The lefty did strike out eight and did not issue a walk.
Boston climbed back into the contest with a three-run seventh inning, as Mike Carp doubled with one out, Jarrod Saltalamacchia singled and Middlebrooks erupted for a three-run homer that closed the visitors' gap to 5-3. Matusz, though, retired the next two batters to keep it a two-run margin.
However, the O's provided some breathing room in the home half. Markakis doubled and was sacrificed to third before Hardy's single brought him in, but they were unable to tack on more runs despite having men on second and third with one out.
Though Jose Iglesias singled to begin the eighth, stretching his hit streak to 17 games, Matusz got the next two men before Hunter induced a Jonny Gomes fly out.
Johnson set the side down in order in the ninth to complete the series victory.
"They don't beat themselves," Boston manager John Farrell said of the rude hosts. "They throw strikes, they're not going to issue many walks. They play very sound defense and they have the ability to score a couple of runs on the swing of a bat."
Baltimore got to Lester in the third, as Markakis hit a leadoff single and scored on Jones' two-out double. Davis followed with a two-run shot to left and the hosts led 3-0.
The blast halted Davis' 0-for-14 string against the Red Sox starter.
Two innings later, the lead grew by two thanks to Machado's RBI single and a two-out run-scoring double from Davis.
Lester's loss left him with a 14-2 career record against the Orioles, which includes a 7-1 record in Baltimore ... Carp left the game in the seventh with right hamstring tightness ... Orioles relievers have tossed 26 total innings against the BoSox this season and have given up only nine hits, four earned runs, one walk and 23 strikeouts ... Actor Richard Gere threw out Sunday's ceremonial first pitch.