The A's scored the winning run in the sixth inning when two runs came in on an error by John Bale on a slow ground ball by Adam Kennedy. Kurt Suzuki and Mark Ellis each drove in a run for Oakland, which won for just the third time in its last eight games.
Alberto Callaspo had two hits and three RBI for the Royals, who lost for the ninth time in 12 games. David DeJesus had three hits, one RBI and two runs scored for Kansas City.
Starter Luke Hochevar (6-8) went 5 1/3 innings, allowing seven runs on six hits to take the loss.