Timbers beat Sounders with goals from Jeremy Ebobisse, Sebastian Blanco

Jeremy Ebobisse and Sebastian Blanco scored first-half goals as the Portland Timbers defeated the visiting Seattle Sounders 2-1 Sunday afternoon in the opening leg of their MLS Western Conference semifinal series.

The second leg of the home-and-home, aggregate-goal series is scheduled for Thursday night in Seattle.

Raul Ruidiaz scored for the Sounders, which could be key, because the first tiebreaker in the event both teams end up even after two games is road goals.

But the Sounders, who won 14 of their past 16 regular-season games to clinch the conference's No. 2 seed into the playoffs and a first-round bye, had to make two first-half substitutions because of injuries.

Midfielder Cristian Roldan suffered a groin injury, and defender Chad Marshall hurt his right knee, with both having to leave the game.

Ruidiaz opened the scoring in the 10th minute. Roldan drove down the left wing and sent in a cross that deflected off a Portland defender and right to Ruidiaz at the top of the 6-yard box. Ruidiaz's right-footed shot found the top of the net.

The fifth-seeded Timbers, who won 2-1 at FC Dallas in the elimination round on Wednesday, tied it on Ebobisse's goal in the 17th minute, assisted by Diego Valeri. From near midfield, Valeri put a through ball to Ebobisse, who beat defender Kim Kee-Hee to the ball and chipped it over goalkeeper Stefan Frei.

Portland made it 2-1 in the 29th minute, as Valeri stole a pass near midfield and drove down the center of the pitch to the top of the 18-yard box, where the ball was knocked off his foot with a sliding tackle by Marshall. Blanco gathered the ball about 15 yards from goal and dribbled to the top left of the 6-yard box, catching Frei flat-footed with a left-footed shot into the lower right corner.

The Timbers appeared to score another goal in the 79th minute, but the play was ruled offside.

The Sounders' Victor Rodriguez had a good scoring chance in the 90th minute, but his 18-yard shot was right at goalkeeper Jeff Attinella.

Although the Seattle-Portland rivalry dates back to 1975 in the old North American Soccer League and encompasses more than 100 matches in all competitions, this is just their second meeting in the MLS playoffs. Portland won the first in 2013.

The Timbers played without defender Larrys Mabiala, who received a red card in the elimination round. He will be eligible to return for Thursday's match in Seattle.