Jake Westbrook (13-10) pitched 7 2/3 strong innings, allowing two runs (one earned) and nine hits, striking out five and getting 14 outs on grounders. His only walk was to the last batter he faced, Frank Thomas. Juan Lara then came on and got the final out of the eighth on one pitch.
Victor Martinez hit a two-run homer, his 16th, in the first inning to start Cleveland on its way to a 7-0 lead.
Casey Blake had a two-out, two-run double in the third, Hector Luna hit his sixth homer to open the fourth, drove in another run with a fielder's choice grounder in the fifth and later scored on a wild pitch to make it 7-0.
Martinez, Blake, Grady Sizemore, Andy Marte and Jhonny Peralta all had four hits. Sizemore went 2-for-3 to raise his career average to .440 (11-for-25) at Oakland. The only member of Cleveland's starting lineup without a hit was Jason Michaels, who did walk and score on Martinez's homer.
Rafael Betancourt retired the A's in order on four pitches in the ninth as Oakland had a four-game winning streak stopped.
Oakland, coming off a three-game sweep of the defending World Series champion Chicago White Sox, had its AL West lead drop to 6 1/2 games over the idle Los Angeles Angels.