VANCOUVER, B.C. – At least one Cascadian club is guaranteed to be in this year's Western Conference Conference Championship. The Vancouver Whitecaps are intent on making sure it is them.

The Whitecaps' 5-0 thumping of the San Jose Earthquakes in Wednesday night's Knockout Round match in the Audi 2017 MLS Cup Playoffs set up a mouth watering semifinal clash with their fierce Cascadian rivals, the Seattle Sounders.

The first leg goes this Sunday in Vancouver (8:30 pm ET | TSN1/4, TVAS2 in Canada; ESPN in the US), with the second leg in Seattle just four days later. 'Caps coach Carl Robinson is expecting a real barnburner of a series.

"I'm sure there'll be emotions, and tackles, and cards, and football, and goals, and penalties," Robinson told reporters after the win against San Jose. "Hopefully from my side. You always get those things with derby games. The focus [against San Jose] was try and get through this round and then go and have a good two-legged series against our rivals."

It will be the first-ever meeting between the two Cascadian rivals in the postseason. In the Whitecaps' only other conference semifinal appearance, in 2015, they lost to the other member of the Cascadian trifecta, the Portland Timbers. It's an experience no one of a 'Caps persuasion wants to live through again.

Robinson knows that Wednesday's result will have fired a shot across the Sounders' bow heading into Sunday, but cautioned against people looking at the five-goal performance and expecting the same against Seattle. As far as he's concerned, the No. 2 seed Sounders are the clear favorites heading in to the series against the third-seeded 'Caps.

"Listen, we're playing against the champs," Robinson said. "We know we're going to be underdogs. I like the underdog role. We've played them three times this year, I'm sure we're sick of the sight of each other. Which is good."

There's certainly three good reasons for Robinson to feel this way – the goals Seattle put past Vancouver a month ago. That 3-0 victory for the Sounders against Vancouver on Sept. 27 was comprehensive.

The Whitecaps feel they can learn a lot from that defeat, and after Wednesday's rout of San Jose, they firmly believe they can get the job done over the two legs.

"When you play against a good team, you cannot make mistakes," said Whitecaps striker and former Sounder Fredy Montero. "All these details, we need to get better. [Against San Jose] we proved that we can score goals. I'm just happy that this result is going to give us more confidence to play against one of the best teams in the league."

Vancouver with be facing a Clint Dempsey-less Seattle in Sunday's first leg after a Decision Day red card. It's a boost for the Whitecaps defense, but rookie right back Jake Nerwinski doesn't care who's on the pitch for the Sounders, or the most recent results between the two teams.

"Dempsey's a great player, he's a veteran" Nerwinski told reporters. "That's definitely going to hurt them a little bit, but they've got enough guys to fill in his shoes, so we're going to have to be on our game too.

"Seattle's a really good team. We know it's a big rivalry. We had a little bit of an off game [last time], but we've played them, we've beaten them this season. We know we can beat them again. That's kind of all we need to look at going forward."