Kurt Suzuki belted two solo home runs to power 5, in the rubber match of game series.
David DeJesus entered the game as a defensive replacement in the top of the ninth and threw out potential tying run at the plate to preserve the win.
Josh Willingham had a two-run double for the A's, who won the last two games of the series after losing four straight.
Brandon McCarthy (6-6) allowed four runs on eight hits over six-plus innings to earn the victory. He walked two and struck out three.
Nick Markakis went 3-for-4 with a home run and two RBI. He singled with two outs in the ninth to score Robert Andino, but pinch runner Blake Davis was cut down at the plate, as Andrew Bailey escaped with his 15th save of the season.
Alfredo Simon (3-6) was touched for six runs -- five earned -- on eight hits in 5 1/3 innings to suffer the loss.