Seattle found themselves in the driver's seat early in the second half after a 48th-minute goal from Cristian Roldan. But León scored three straight after that, with Ángel Mena tallying a brace before Emmanuel Gigliotti bagged a late rebound finish that rendered a late consolation tally from Seattle's Nicolas Benezet a moot point.
León had perhaps the best look for either side in the first half right on the stroke of halftime off a Mena corner kick that found Jean Meneses free at the far post. Meneses drove the subsequent header into the ground but saw it go just wide of Seattle goalkeeper Stefan Frei, allowing the Sounders to narrowly avoid conceding the opener.
The action really took off in the second half, starting with Roldan's huge opener that put Seattle on top 1-0. The US international midfielder redirected home a cross from Jimmy Medranda after Raul Ruidiaz played him into space down the left side.
That opened the match right up, with Seattle creating a couple of good chances to double their lead in the immediate aftermath, most notably a golden opportunity from Ruidiaz that the Peruvian smashed off the post.
That miss proved significant, as León equalized just as the contest passed the hour mark. It was Mena who atoned for his earlier miss, cashing home a feed from Elías Hernández right on the doorstep.
León then got the go-ahead tally from the penalty spot nine minutes from full time after Seattle's Shane O'Neill was whistled for a foul in his own area, allowing Mena to convert from 12 yards out. Gigliotti added the Liga MX side's final goal, pouncing on the rebound after Frei saved an initial breakaway shot.
Seattle earned one last lifeline when Benezet's deflected shot found the net during second-half stoppage time, but Ruidiaz saw one last-gasp look at a dramatic leveler go just wide.
- THE BIG PICTURE: There's no shame in coming up short against a team of Club León's quality, but Seattle will be frustrated at how this one ended. They held the lead after Roldan's opener and the pair of goals they gave up to go down 3-1 were preventable. Seattle can take pride in topping two Liga MX foes to reach this point and giving León everything they could handle, but the sting at missing out on the club's first international trophy might linger for a while.
- MOMENT OF THE MATCH: This is the type of finish that Ruidiaz makes his living on, and if it had gone in, the Sounders would have been up 2-0 and likely would have lifted the trophy at the end of the night.
- MAN OF THE MATCH: Ángel Mena gets the honors for pacing his team with a brace during an all-around dynamic performance.
- SEA: Sunday, September 26 at Sporting Kansas City | 7 pm ET (FS1, FOX Deportes)