Galaxy, who progressed after a 2-2 draw on aggregate, will meet the New England Revolution in the final and will be looking for a record fifth MLS title at their own stadium on December 7.     

In freezing temperatures in Seattle, the Sounders, trailing 1-0 from the first leg in Los Angeles, opened the scoring in the 27th minute when a Clint Dempsey effort fell to Brad Evans, who slid the ball home from close range.           

Five minutes later former Fulham striker Dempsey put Seattle 2-0 up with a shot that took a slight deflection and snuck under Galaxy goalkeeper Jaime Penedo, who will be disappointed he failed to smother the ball.            

The artificial surface made it difficult for both sides to keep possession but there was no shortage of action or tension after the break.            

Galaxy striker Robbie Keane went close with a curling shot that Sounders’ keeper Stefan Frei pushed wide, but L.A. got the decisive goal in the 54th minute when midfielder Juninho crashed home a first-time effort from 20 yards that went in off the post.            

This is the first year that MLS has included the away goals rule in their playoffs, although that aspect would have been irrelevant if not for some fine work from Frei, who did well to keep out a Landon Donovan shot and a header from Stefan Ishizaki            

Roared on by a 46,758 crowd, Seattle threw themselves into a series of late attacks but when their best chance fell to Dempsey, he volleyed wide.            

The result means that Donovan, who has announced he will retire at the end of the season, has the perfect farewell opportunity with the title-decider at his home field.