Reddick was hitless in his previous 20 at-bats before connecting off Esmil Rogers with a solo blast in the second inning that hit the facing of the second deck in right. He hit another solo homer in the fifth, an opposite field shot to left off reliever Neil Wagner, then smacked a three-run drive off Juan Perez in the sixth.
The home runs were the sixth, seventh and eighth of the season for Reddick, who has three career multihomer games. All three homers came with two outs.
It's the first three-homer game by an Athletics player since Erubiel Durazo did it in a 5-4 win at Baltimore on Aug. 18, 2004, hitting a pair of two-run homers and a solo shot.