Both teams have four games remaining including the final two against each other: Oct. 19 at LA and Oct. 25 at CenturyLink.
Before that, the Galaxy has a home game with Toronto on Saturday and a visit to Dallas on Oct. 12.
The Sounders visit Colorado on Sunday and host Vancouver on Oct. 10.
Seattle has two more wins than LA, which is the first tie-breaker. But Los Angeles has a staggering 15-goal advantage in goal differential, which is the second tie-breaker.The Sounders are off today and return to training Tuesday.