Jordan Morris scored in the second half and the Seattle Sounders advanced to the MLS Cup final for the first time with 1-0 win at the Colorado Rapids on Sunday.
Morris' strike in the 56th minute opened a two-goal advantage for the Sounders after last week's 2-1 win in the first leg, and they advanced 3-1 on aggregate while handing the Rapids their first home loss of the season.
The Rapids, entering the game knowing they needed a goal, had all of the early pressure as Jermaine Jones lashed an early shot off-target before his glancing header from a corner also fell wide of the net.
Midway through the first half, Kevin Doyle had a chance when he raced onto a long pass, but his ball through the six-yard box went untouched.
Jones remained dangerous, looping another shot high following a corner and delivering a cross to Shkelzen Gashi, who had space in the box but decided to try for a spectucular volley that he could not keep on target.
Sounders coach Brian Schmetzer, who took over in midseason after Sigi Schmid was fired, decided to show more signs of attack after halftime and was rewarded by Morris' goal within 11 minutes.
Nelson Valdez played Morris in on goal with a through ball, and the former Stanford star took a touch before beating Colorado goalkeeper Zac MacMath with the outside of his boot.
Morris stayed down after colliding with MacMath, who was playing in place of the injured Tim Howard, but he quickly returned to action after having his knee taped on the sideline.
Seattle's Osvaldo Alonso was not so fortunate after picking up an injury and had to be replaced by Oniel Fisher in the 74th minute.
With Morris' goal, Colorado needed two goals to force extra time but despite increased pressure could not find a clear opportunity in the final quarter-hour.
Seattle has qualified for the playoffs in each of their eight seasons in MLS but had never before made the final. The Sounders had twice made it to the conference final but fell to the LA Galaxy in both 2012 and 2014.
They will host the Dec. 10 final if the Montreal Impact hold on to beat Toronto FC in the Eastern Conference final. Toronto will host the final if it can overturn a 3-2 deficit in the second leg on Wednesday.