Seattle surrendered two goals to Robbie Keane and one to Mike Magee, while being blanked on offense despite holding an edge in time of possession.Goalkeeper Michael Gspurning limited the damage, stopping three Galaxy shots.
The loss leaves the Sounders needing a win by four or more goals next Sunday when they host L.A. at Livestrong Sporting Park. Seattle, though, has already accomplished the feat once when it topped the Galaxy 4-0 at home on Aug. 5.
In the regular season, the Sounders were 2-1 overall against L.A. with a 6-1 edge in scoring. They finished one spot above the Galaxy in the standings, earning the No. 3 seed with a 15-8-11 record.