Griffin, A's blank Red Sox, 3-0
Derek Norris homered and Yoenis Cespedes and Coco Crisp had RBI singles for the Athletics, who defeated the Red Sox at home for the seventh time in the last eight meetings.
Griffin (8-6) yielded six hits and a walk while striking out three.
He left runners in scoring position in the first, third, fourth and sixth innings before retiring the last seven men he faced and turning it over to Grant Balfour, who converted his 25th save and 43rd in a row dating back to 2012.
Lester (8-6) matched zeroes with Griffin until serving up the home run to Norris with two outs in the fifth.
The lefty was charged with three runs in 6 1/3 innings, recording just his third quality start in his last eight outings.
Cespedes followed a walk and a single in the sixth with his run-scoring hit and Crisp greeted Junichi Tazawa with a bloop to right field in the seventh to make it 3-0.
Josh Reddick had two hits and scored on Crisp's single.
GAME NOTEBOOK: The Red Sox officially added LHP Matt Thornton to the active roster and optioned RHP Steven Wright to Triple-A Pawtucket. Thornton was acquired in a trade with the Chicago White Sox on Friday. ... Oakland ended its first two-game slide since June 22-23. It has not dropped more than two in a row since a five-gamer May 6-10.