Landon Powell also homered for the A's.
Winning pitcher Gio Gonzalez (5-5) allowed two runs and six hits in seven innings.
Jose Lopez and Adrian Beltre singled in the Seattle runs.
Reliever Shawn Kelley (4-2), victim of Hairston's blast, was the loser.
Seattle's Ichiro Suzuki collected the 2,000th hit of his major-major career, a double to right field in the first inning.
Copyright 2009 by United Press International.