SEATTLE — Nicolas Lodeiro scored on a penalty kick in the 61st minute and the Seattle Sounders beat the Colorado Rapids 2-1 on Tuesday night in the first-leg of the MLS Western Conference finals.

Seattle will take an important one-goal advantage into the second match of the two-game series on Sunday in Colorado. But the Rapids picked up an important road goal which could serve as the tiebreaker if the aggregate-goal series finishes tied. A win or a tie by Seattle on Sunday would put the Sounders in the MLS Cup final for the first time.

Lodeiro caused issues all over the field for Colorado before drawing the penalty 15 minutes into the second half. A deflected ball rolled to Lodeiro in the penalty area and he was taken down by Marc Burch. Lodeiro sent goalkeeper Zac MacMath the wrong direction and scored his fourth goal of the playoffs.

After a 16-day layoff due to a break for international competition, what was expected to be a defensive struggle was instead a lively showcase that featured chances on both ends.

Kevin Doyle gave Colorado an early advantage when his shot in the 13th minute deflected off Seattle defender Chad Marshall and past goalkeeper Stefan Frei, stunning the 42,774 in attendance for the Sounders' third appearance in the conference finals. Doyle was able to get free thanks to a smart decision by Shkelzen Gashi letting the pass from Jermaine Jones run through.

Seattle responded almost immediately with Jordan Morris pulling the Sounders even in the 19th minute jumping on the rebound of Cristian Roldan's shot that beat MacMath but ricocheted off the post. Seattle was unsure if Morris would play after suffering an hamstring injury in the second-game of its semifinal win over FC Dallas. The injury kept Morris from joining the U.S. national team for its qualifying matches against Mexico and Costa Rica.

MacMath did his part making his first start since Sept. 3 with Tim Howard out for the year after undergoing surgery for an adductor injury suffered with the U.S. during the loss to Mexico. MacMath made four saves, none better than a sequence midway through the first half where he pushed aside a header from Lodeiro and off the ensuing corner kick smothered Nelson Valdez's shot at the back post.