Athletics 4, Mariners 1: Pinch hitter Chris Carter walloped a three-run homer in the bottom of the 11th inning to give Oakland its fifth straight victory.

Carter crushed the second pitch he saw from Seattle reliever Steve Delabar as the Athletics reached .500 with their seventh walkoff victory of the season.

Josh Reddick led off the 11th with a flare into left field off Oliver Perez (0-1) that dropped in front of Casper Wells and Seth Smith reached on a check-swing infield hit down the third-base line with one out. Carter then hit the no-doubt blast deep into the left-field seats for his third homer of the campaign, stretching Oakland’s consecutive games streak with at least one homer to 16.

Jordan Norberto (1-1) struck out the side in the top of the 11th for the Athletics.

Oakland tied the score in the eighth when pinch hitter Brandon Hicks narrowly missed a game-tying homer while doubling off the right-center field. Tom Wilhelmsen entered with two outs and allowed a tying single to center by Jemile Weeks.

Starters Kevin Millwood and Tommy Milone engaged in a pitcher’s duel for seven innings.

Millwood didn’t allow a run, giving up three hits and two walks while striking out seven. Milone struck out a career-best nine in his seven-inning stint, allowing one run on six hits and one walk. His home ERA rose to 1.03 despite the stellar outing.

Seattle put together three singles in the first inning before Milone settled down. Wells singled with one out, moved to second on Miguel Olivo’s two-out single before Kyle Seager singled to center field to drive in Wells.

GAME NOTEBOOK: Seattle C Jesus Montero (concussion) wasn’t in the lineup Friday but won’t be going on the seven-day concussion disabled list because of the upcoming All-Star break. … The Athletics won for the first time in three attempts against the Mariners in Oakland this season. ... Seager has recorded 34 of his 49 RBIs on the road. … Milone is 5-1 in seven home starts.