Vancouver Whitecaps are chasing a place in the playoffs themselves and will confirm their spot in the top seven if they avoid defeat to Seattle.
A stellar Western Conference campaign for Seattle looks set to finish with the side topping the table, whilst securing a pass into the CONCACAF Champions League for next year.
It is just the second time in their Major League Soccer history that they have topped the Western Conference come the end of the regular season, having emulated the feat that they first managed in 2014.
That season ended in a MLS Cup heartbreak, and the Sounders will head into the playoffs confident of going the distance this time around.
A constant in the playoffs since their MLS induction in 2009, the Sounders are no strangers to success, with only two sides having won more US Open Cups than the Washington State-based outfit.
Chasing their third MLS Cup, the Sounders are once indebted to long-time manager Brian Schmetzer, who took charge of the club in 2016 and has overseen 206 matches as the Seattle coach.
Their previous two MLS Cup wins came under the Seattle-based coach and Schmetzer will be keen to make it three in five years when the playoffs commence.
There is a still a chance they could drop out of top spot in the Western Conference before the playoffs roll around, with Sporting Kansas City and Colorado Rapids both just one point behind the Sounders.
A win against the Whitecaps would secure the Western Conference title, and they will be hoping to replicate the scoreline from the previous meeting with the Vancouver-based outfit.
The Whitecaps have their own ambitions heading into the fixture, needing at least a point to ensure that they finish the regular season inside the top seven spaces.
Currently sitting in sixth, Vancouver have a three-point advantage over eighth-placed Real Salt Lake, with a draw enough to take them onto 49 points and into the playoffs.
Much jeopardy lies on this fixture, with at least one side set to have a nervy end to the campaign, and the history books would suggest Seattle should be the most confident.
Unbeaten against the Whitecaps since April 2017, Seattle have played 12 times against Vancouver without losing and the Sounders will be keen to extend that record to 13 this weekend.
What is more, out of those 12 fixtures only four have finished in draws, meaning the Whitecaps may have to hope for a favour elsewhere if they are to qualify for their first playoffs since the 2017 campaign.
Much of the Whitecaps' strong form this season has been down to the performances of Brian White, who leads the scoring chart for Vancouver with 12 goals.
A broken ankle picked up in mid-August has kept Caio Alexandre out ever since, but the Brazilian midfielder has hopes of returning to the Whitecaps side should they progress to the playoffs.
Andy Rose is another absentee for the Seattle match who will targeting a return for the playoffs, with the 31-year-old currently suffering with a calf injury, which is the same issue facing Tosaint Ricketts.
Relatively good luck with injuries has helped Seattle to the position they are currently in, with their standout performer Raul Ruidiaz a crucial part to the Sounders success.
The Peruvian has scored 17 times in the league this season and keeping the 31-year-old forward quiet will prove a difficult task for an often leaky Whitecaps defence.
Vancouver Whitecaps possible starting lineup:
Crepeau; Godoy, Jungwirth, Nerwinski; Gasparm, Teiber, Owusu, Brown; Gauld, White, Dajome
Seattle Sounders possible starting lineup:
Frei; Gomez, Arreaga, Tolo; Roldan, Paulo, Rowe, Smith; Roldan, Lodeiro, Ruidiaz
We say: Vancouver Whitecaps 1-1 Seattle Sounders
Much rests on the result of this game and both Seattle and Vancouver will be desperate to avoid the uncertainties of defeat when they meet on Sunday.
Seattle lead the Western Conference and thus enter the match as favourites, yet Vancouver know their playoff hopes rest on a result, making this one an extremely tight affair.
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