VANCOUVER, British Columbia (AP) - The Vancouver Whitecaps and Seattle Sounders combined for just one shot on target in a scoreless draw to open their Western Conference semifinal on Sunday night.
Vancouver, which missed the MLS playoffs by eight points last season, and Seattle, winners of the 2016 MLS Cup, kept things tight to the vest with neither team willing to take many risks.
The second leg of the two-game aggregate series is Thursday at Seattle.
The Whitecaps, who finished third in the West standings, were coming off the club's first-ever playoff victory - a 5-0 demolition of the San Jose Earthquakes in Wednesday's single-elimination knockout round.
The Sounders, meanwhile, won three of their last four to close out the schedule, including a 3-0 home win over Vancouver on Sept. 27 to grab second in the conference and secure a bye to the semis.
Vancouver made two big changes to the starting lineup that thumped the Earthquakes, with crucial offensive pieces Yordy Reyna and Cristian Techera forced to the bench after getting injured against San Jose.
Brek Shea and Nosa Igiebor, who only signed last month and made his second appearance, slotted into midfield alongside Christian Bolanos in support of striker Fredy Montero.
The Sounders, meanwhile, were without leading scorer Clint Dempsey after he was red carded in the club's regular-season finale, while fellow striker Jordan Morris (hamstring) was among Seattle's walking wounded.
Sounders defender Chad Marshall rose to head the match's one and only shot on target in the 48th minute, but goalkeeper Stefan Marinovic was there to make a comfortable save.
Reyna subbed on in the 62nd minute to raucous applause before Techera joined the fray in the 76th, but their introductions did little to add any more attacking flair to a game that seemed destined to end 0-0 from the early stages.
Things got heated in the 83rd minute with the Whitecaps clearly annoyed at what they viewed as time wasting by the Sounders, with Vancouver captain Kendall Waston in the middle of it.
Seattle had the only real opportunity at a breakthrough in the 35th minute when Joevin Jones got in behind Whitecaps right back Jake Nerwinski and fed a dangerous low cross that Waston rattled off his own crossbar for what was nearly a demoralizing own goal.
The Whitecaps, who wound up a point behind Seattle, beat the Sounders 2-1 at home on April 14 and fought back after having a player sent off to secure a 1-1 draw at B.C. Place on Aug. 23.
The Whitecaps opened most of the stadium's lower bowl, which pushed attendance to 27,837 and created an electric atmosphere that was helped by a strong contingent of Sounders supporters.
NOTES: Dempsey is eligible to return for the second leg. ... The Portland Timbers, ranked No. 1 in the West, visit the No. 4 Houston Dynamo in the first leg of the other conference semifinal on Monday.