FOLLOW LIVE — Whitecaps host Sounders in West semis, leg 1

Darryl Dyck/The Canadian Press via AP

The first of four 2017 MLS Cup Playoffs conference semifinals kicks off on Sunday (8:30 p.m. ET), when the Western Conference’s third-seeded Vancouver Whitecaps play host to one of their Pacific Northwest rivals, the second-seeded Seattle Sounders, in the first of two legs.

[ FOLLOW: Whitecaps vs. Sounders — leg 1 ]

Vancouver reached the conference semis by brushing aside the San Jose Earthquakes, 5-0, in the knockout round on Wednesday. Fredy Montero and Cristian Techera got the all-important first two goals before Kendall Waston and Nicolas Mezquida (twice) poured it on late.

Seattle will be without Clint Dempsey, who was sent off in the Sounders’ regular-season finale for a petulant elbow to the head of Colorado Rapids Mike da Fonte. Following Dempsey being shut down (irregular heartbeat) for the remainder of the regular and postseason, Seattle went on to win MLS Cup 2016.

[ FOLLOW: All of PST’s MLS coverage ]

Regular-season matchups: Whitecaps 2-1 Sounders (Apr. 14), Whitecaps 1-1 Sounders (Aug. 23), Sounders 3-0 Whitecaps (Sept. 27)