Lester (17-8) has won four straight decisions and six of his last seven starts. He gave up three singles, two to Chone Figgins, walked three and struck 12. It's the seventh time this season he has struck out 10 or more.
Lester now is tied for second in the American League in wins. He is third in strikeouts (208), eighth in ERA (3.17), and tied for third in opponents batting average (.220).
Daniel Bard took over in the ninth. He allowed a one-out single to Jose Lopez. Casey Kotchman then hit into a fielder's choice and Matt Tuiasosopo struck out.
In his last start July 24 at Safeco Field, Lester retired the first 17 batters but the Mariners rallied for a 5-1 victory. Lester struck out a career-high 13.
The Red Sox took a 3-0 lead in the second, hitting three doubles. Adrian Beltre singled to open the inning. Jed Lowrie doubled, sending Beltre to third. He came home on Josh Reddick's groundout. Daniel Nava and Lars Anderson followed with consecutive RBI doubles.
Ryan Kalish added a two-run homer in the eighth off Doug Fister (5-12).
The Mariners scored their run in the seventh. Franklin Gutierrez drew a one-out walk. Lopez singled to left, pushing Gutierrez around to third. He scored on Kotchman's infield groundout.
The Red Sox have added LHP Rich Hill to their roster. Hill, a five-year veteran whose best year was 2007 when he was 11-8 with the Cubs, signed as a free agent on June 30. He had been released from the Cardinals organization. "Maybe it's a nice chance to learn more about him," Sox manager Terry Francona said. … J. D. Drew missed the game with a slightly sprained ankle. He turned his ankle rounding first base Sunday. … Mariners closer David Aardsma is one save short of getting 30 for the second straight season. He had none before last year. "He's taken to that job. He understands it," manager Daren Brown said. "It takes a special type person to come in at the end of the ball game. Things don't bother him and he's able to get the job done."