SEATTLE -- Ryan Johnson flicked in a header early in the first half, and Darlington Nagbe scored midway through the second half on Saturday night as the Portland Timbers beat the Seattle Sounders 2-1 in the first leg of their Western Conference semifinals series.
The third-year Timbers, playing in their first MLS post-season contest, need just a draw in Wednesday's second leg at Portland to advance to the conference finals.
Osvaldo Alonso scored in the 90th minute for the Sounders, who need to win the second leg by at least two goals to win the aggregate total and advance.
If the Sounders outscore the Timbers by one goal in the second match to even the aggregate total, there would be overtime to decide the series.
Diego Chara started the play that led to Portland's first goal with a long pass toward the right side. Jack Jewsbury was on the receiving end and took it deep into the corner. He crossed it into the penalty area, and Johnson, cutting across goalkeeper Marcus Hahnemann's 6-yard box, flicked a header that went off Hahnemann's hands and into the far side of the net early in the 15th minute.
Johnson's goal was his 10th of the year for the Timbers, who went unbeaten through their last eight games of the regular season (5-0-3) to secure the West's No. 1 seed.
Nagbe made it 2-0 in the 67th minute. Kalif Alhassan, playing on the right side, sent the ball into the box. Nagbe spun around a Seattle defender and parked a shot past Hahnemann into the left side for his 10th of the year.
Alonso got one back for Seattle late after a long throw-in by Brad Evans was re-directed by Shalrie Joseph out to Alsonso, who drilled it in past Timbers goalkeeper Donovan Ricketts from 14 yards straight in front for his first of the season.