Napoli now leads the Indians with 23 home runs. With the victory, Cleveland remains 4 1/2 games ahead of the Tigers in the division.
Billy Butler belted a towering home run for Oakland, but his shot off Tomlin -- one followed by a dramatic bat flip -- caused tempers to flare momentarily in the fourth. After Butler's homer knotted the score, A's starter Dillon Overton was unable to keep the Tribe in check. In 3 1/3 innings, Overton allowed five runs, including three in Cleveland's four-run fourth.
Marcus Semien added a solo shot off Indians closer Cody Allen in the ninth, giving the A's shortstop 22 homers.