Felipe Mora had a goal and an assist as Portland defeated the host Seattle 2-0 Sunday night in the Timbers' first win against the Western Conference-leading Sounders in three meetings this season.
Sebastian Blanco also scored as the Timbers (8-10-3, 27 points) won for just the second time on the road this season (2-7-2) and avenged a 6-2 defeat at home to the first-place Sounders (12-4-6, 42 points) two weeks earlier.
Portland goalkeeper Steve Clark, who missed the previous match with an injury, made five saves for the shutout.
Both goals came after Seattle defensive miscues.
In the 58th minute, the Sounders' Yeimar Gomez Andrade attempted to make a pass back to goalie Stefan Cleveland, but Mora intercepted it near the top of the 18-yard box. Mora dribbled the ball near the end line on the left wing and threaded a pass between Cleveland and defender Xavier Arreaga to Blanco, who was alone at the top of the 6-yard box and tapped the ball into an open net.
The second goal came in second-half stoppage time. Cleveland, well out of the penalty area, tried to head the ball away but it went straight up in the air. Mora won a battle for the ball with Andrade and chipped it over a retreating Cleveland from about 25 yards out.
Seattle's Joao Paulo had two strong chances from just outside the 18-yard box in the opening 15 minutes of the second half, but the first went off the crossbar and the second was tipped over the bar by Clark.
Clark also made a diving save off a 20-yard shot by league scoring leader Raul Ruidiaz in the 86th minute.
Portland's Dairon Asprilla also found the woodwork, putting a 30-yard shot from the left wing high off the right post in the 6th minute.
Timbers midfielder Eryk Williamson, a U.S. international, suffered a leg injury in the ninth minute and had to be replaced. Williamson was attempting a pass near midfield when he went down without an opponent in the vicinity. He briefly got to his feet and tried to walk away before being stretchered off the pitch.