By DAN KARELL

For the second time in four days, the Vancouver Whitecaps will be playing with their playoff hopes on the line, knowing that just about anything but a victory against the Seattle Sounders will mean that vacation begins on Oct. 28.

The Sounders have dropped points in two matches in a row but are getting healthier this week and will have both Clint Dempsey and Obafemi Martins available to play, a luxury that wasn’t afforded to Sigi Schmid’s squad Saturday in Colorado. The Sounders can clinch a playoff spot themselves on Wednesday with a win or a San Jose Earthquakes loss.

Elsewhere in MLS, the Earthquakes host the on-fire Colorado Rapids. The Rapids will be without Deshorn Brown and Gabriel Torres due to international call ups. The Houston Dynamo face Sporting Kansas City in a rematch of last season’s Eastern Conference playoff finals.

Here is a rundown of the Wednesday night slate:

HOUSTON DYNAMO vs. SPORTING KANSAS CITY (8:30pm, MLS Live)

Revenge will surely be in the mind of the Dynamo players when they take the field on Wednesday evening against Sporting KC. The last time these two squads met at BBVA Compass Stadium, Peter Vermes’ side ended the Dynamo’s 36-game home unbeaten run with a 1-0 victory.

This time around both teams will be missing key pieces due to international matches as Oscar Boniek Garcia and Jermaine Taylor miss out for the Dynamo and Sporting KC lose Graham Zusi and Matt Besler to the U.S. Men’s National Team. Paulo Nagamura remains out though Claudio Bieler is listed as questionable.

SEATTLE SOUNDERS vs. VANCOUVER WHITECAPS (10pm, TSN2/MLS Live)

There’s more than just pride and playoff hopes on the line when the Sounders host the Whitecaps at CenturyLink Field. The Sounders can not only clinch a playoff place with a win against their Pacific Northwest foes, but can also reclaim the Cascadia Cup with a win or a tie, bringing the trophy back to Seattle for the first time since 2011.

The Whitecaps can hardly afford a defeat at the Sounders as they sit six points out of a playoff place with three games remaining. They’ll be buoyed by the Sounders’ loss of Zach Scott with a red card suspension and likely Leo Gonzalez to injury. However, the Sounders should have the services of Clint Dempsey and Obafemi Martins.

SAN JOSE EARTHQUAKES vs. COLORADO RAPIDS (10:30pm, MLS Live)

Like the Whitecaps, the Earthquakes can ill-afford a defeat when they host the Rapids at Buck Shaw Stadium on Wednesday evening. The ‘Quakes are four points behind the Rapids, but of course a win would give them at least a chance of sneaking into the playoffs late in the season.

The Earthquakes will be without Victor Bernardez and Marvin Chavez, while the Rapids will miss strike duo Gabriel Torres and Deshorn Brown, all to international selections. Dillon Powers is also ruled out, and Steven Lenhart is suspended due to a red card awarded in the Earthquakes last match.