Oakland lost for just the sixth time in 27 games since the middle of May.
Saunders (5-6) struck out four while throwing 98 pitches and left the game with a 2-1 lead. Oliver Perez, who has been turned into a reliever during the past two seasons after working as a starter for the first nine years of his career, was called on in the ninth and earned his first major league save.
Mike Zunino gave Seattle the lead for good with a solo homer in the seventh and Nick Franklin scored an insurance run in the eighth on an infield single by Raul Ibanez.
The run by Franklin turned out to be the winning one after Oakland came up with a homer from Chris Young in the bottom of the eighth.
Tommy Milone (6-6) took the loss, giving up two runs on five hits in 6 2/3.