Wilson Betemit belted a grand slam to power the Kansas City Royals to a 6-3 victory over the visiting Oakland Athletics in Wednesday's rubber game of a three-game series.

Billy Butler added a two-run homer for the Royals to help Bruce Chen (10-7) reach 10 wins for just the second time in 12 seasons.

Betemit erased a 3-0 deficit with his third-inning slam off Athletics starter Trevor Cahill (16-7), who had not allowed a run in his past two starts.

For the series, Betemit finished 7-for-12 with two home runs and eight RBIs.

Chen overcome a shaky start and went five innings, allowing three runs on six hits while striking out two and walking one.

Joakim Soria, Kansas City’s fourth reliever, finished up for his 38th save.

Matt Carson hit a solo homer and Mark Ellis and Kurt Suzuki added RBI singles for Oakland.

Cahill was tagged for six runs on six hits in five innings. He struck out three and walked four.