The Sounders have rocketed up the playoff spots, and with a win over Chivas, are now threatening the Supporters' Shield.
Lamar Neagle scored Seattle's winner in the 24th minute.On the end of Marc Burch's free kick into the box, he received the ball, turned and shot past Dan Kennedy all in one fluid motion.
The win, which keeps the Sounders (13-8-4) third, ties them on 43 points with the LA Galaxy and brings them closer to first-place Real Salt Lake on 48 points. Seattle has also played the fewest games in the conference, 25.
Chivas USA (5-15-7), on 22 points, is in last place in the West.