PORTLAND, Ore. — Sebastian Blanco put the Timbers in front with a goal in the 29th minute and Portland hung on over a tense second half to go up 2-1 in the first leg of their Western Conference semifinal against the Seattle Sounders on Sunday.
The second leg is set for Thursday night in Seattle. The Sounders were hurt by a pair of key injuries in the opening half that forced them to use two substitutions.
Seattle, the second seed in the West, avoided the knockout round after wrapping up the regular season with a 2-1 victory over the San Jose Earthquakes. The win, secured on a Raul Ruidiaz stoppage-time goal, combined with Colorado's Decision Day victory over FC Dallas, slid the Sounders into second place in the standings.
The Sounders won 14 of their final 16 regular-season games in another remarkable second-half surge under coach Brian Schmetzer.
Fifth-seeded Portland lost its final regular-season match against the Whitecaps and had the daunting task of facing FC Dallas on the road in the knockout stage. But the Timbers pulled off a 2-1 upset with a pair of goals from Diego Valeri, despite playing for much of the second half a man down.
The victory set up the Cascadia semifinal between the two teams, who last met in the 2013 conference finals with Portland winning 5-3 on aggregate.
Ruidiaz scored in the 10th minute to give the Sounders the early lead. Cristian Roldan moved the ball up the left side and passed it off to Victor Rodriguez, who served it into Ruidiaz out in front of the goal. Ruidiaz tucked his shot into the left side of the net out of Jeff Attinella's reach. It was his 11th goal this season.
But the Timbers pulled even a short time later on Jeremy Ebobisse's goal. Stefan Fry rushed Ebobisse and slid to try to stop the ball, but Ebobisse got it past him and the shot sailed into the net.
Blanco maneuvered around several defenders before a clinical finish out of Frei's reach to put Portland in front.
Roldan had to leave the game in the 31st Minute with a groin injury. He was replaced by Waylon Francis. Seattle also lost midfielder Chad Marshall, who had to be stretchered off the field with a right knee injury. He was replaced by Roman Torres in the 40th minute.
The Timbers thought they had another goal in the 80th minute on Lucas Melano's rebound but it was called offside.
The two teams met three times during the regular season, but Seattle won the last one 1-0 at Providence Park.
Portland was without Larrys Mabiala after he was sent off with a red card in the match against Dallas.