Albert Rusnák scored on a penalty kick, Jordan Morris added an insurance goal and Stefan Frei posted his 12th career clean sheet in the postseason as the Seattle Sounders beat FC Dallas 2-0 in a series opener.
Yohei Takaoka finished with five saves for Vancouver to offset Stefan Frei's league-leading 13th clean sheet of the season as the Whitecaps played the Seattle Sounders to a scoreless draw.
Cristian Roldan scored a goal that help Seattle Sounders clinched a spot in the postseason and snapped a four-match winless streak at home with a 2-1 victory over the Los Angeles Galaxy.
Cristian Espinoza scored on a first-half penalty kick and assisted on a second-half goal by Miguel Trauco to lead the San Jose Earthquakes to a 2-0 victory over the Seattle Sounders.
Jeremy Ebobisse scored out of the gates in the second half and Daniel de Sousa Brito made it stand up as the San Jose Earthquakes snapped a 14-match winless skid on the road with a 1-0 victory over the Seattle Sounders.