The Athletics chipped away at the lead, drawing to within one run on Chris Young's second homer of the day -- a solo shot in the eighth. Andrew Bailey struck out the side in the ninth to record his fifth save, securing a victory in the rubber match of a three-game home series.
Jon Lester (4-0) overcame six walks to earn his fourth win in five starts beginning the season, surrendering three runs on six hits over 5 2/3 innings. The left-hander struck out five.
Stephen Drew knocked in a pair of runs for Boston.
A's starter Brett Anderson (1-4) was tagged for six runs on eight hits over four innings.
Young smashed a three-run homer in fourth and finished with four RBI. Jed Lowrie went 3-for-5 with a run scored for Oakland.