The Los Angeles Galaxy did enough on Sunday to book a return trip to the MLS Cup, where the reigning champions will again face the Houston Dynamo in Major League Soccer's title match.
Despite a 2-1 defeat to the Seattle Sounders in the second leg of the Western conference final, the Galaxy advanced 4-2 on aggregate.
Houston, who lost to the Galaxy in last year's MLS Cup final, earlier played DC United to a 1-1 draw at RFK Stadium in the return leg of the Eastern Conference final to advance 4-2 on aggregate.
Los Angeles had taken a firm grip on the Western Conference tie with a 3-0 home win a week earlier, but the Sounders made it clear early they didn't intend to go quietly.
Eleven minutes into the contest, Eddie Johnson appeared to score from close range but was ruled offside.
A minute later, however, Johnson held off Galaxy defender Omar Gonzalez and slipped a shot past Los Angeles keeper Josh Saunders.
The Sounders, their vocal fans undaunted by pouring rain, kept the pressure on but didn't score again before half-time.
Zach Scott header from a corner made it 2-0 in the 57th minute, and the Galaxy's aggregate lead was down to just one goal.
Ten minutes later, however, the referee awarded Los Angeles a penalty when Republic of Ireland international Robbie Keane's attempted cross was blocked by the outstretched arm of Adam Johansson.
Keane calmly converted the penalty in the 68th minute - giving the Galaxy breathing room with what proved to be the final goal of the night.
"I think the guy put his hand out," said Keane, who had immediately appealed for a penalty that provoked bitter complaints from the Sounders.
"It happened so quick," Keane said. "At the end of the day, we're through. And that's the main thing."
Because they finished the regular season with more points than Houston, the Galaxy will host the Dynamo at the Home Depot Center in the MLS Cup final on 1 December.
The Galaxy won their championship clash at the same venue last year 1-0.
In Washington, Houston's Boniek Garcia opened the scoring in the 33rd minute, slotting the ball past DC United goalkeeper Bill Hamid from close range after a pass from Brad Davis.
Facing a three-goal aggregate deficit, United managed just one late goal from Branko Boskovic.