Carl Robinson made only one change to his starting line-up and that was a forced one, with Sebastian Fernandez suspended. That paved the way for Kekuta Manneh to come in to where he made headlines around the world with his hat-trick heroics almost a year ago to the day.
Like that game, Seattle carried the early play and Lamar Neagle had the first shot of the game just 70 seconds in, with a low drive that David Ousted easily held.
The home controlled possession without really threatening the Whitecaps' goal, with Obafemi Martins having a half chance 20 minutes in, but Steven Beitashour reacted quickly to block his shot.
Manneh had been pretty easily contained this time around, but he showed what he was capable of on the half hour mark, when he collected the ball, cut inside and fired off a low shot that Stefan Frei had to turn round his near post.
Vancouver's defence were holding solid as Seattle tried to turn up some pressure and with the Whitecaps squad already depleted, it looked like things may go from back to worse when Manneh went down injured with minutes of the half remaining.
The Gambian hobbled off after treatment, only to come back on seconds later and open the scoring in an amazing turnaround in the 45th minute.
Pedro Morales found Manneh in loads of room on the right and the speedster, fuelled by adrenalin, ran at the Sounders defence, turned inside Chad Marshall and buried it low under Frei for the opening goal of the game.
Manneh pulled up hobbling in his celebrations and with the half time whistle coming shortly after, he hit the deck again and had to be carried off the pitch by two Whitecaps trainers.
That was perhaps the Whitecaps most important half of the season. Now came the next one.
Manneh was unable to come out for the second half, which meant a debut for the Caps' new homegrown signing Kianz Froese. What a game and what an atmosphere to make your MLS debut.
The Caps pushed for a quick second right at the start of the second half and Erik Hurtado nearly got it when he was sent clear but was denied by the legs of Frei to keep it a one goal game.
It was to be a nervy period after that with Seattle pressing but Vancouver keeping them comfortably at bay.
There were some edge of the seat moments at the minutes ticked down, the closest of which came in stoppage time when Kendall Waston cleared a Brad Evans header off the line.
The Caps killed the game of to perfection though to once again sit in the driver's seat in the race to the playoffs.
Two Cup Finals left.
FINAL SCORE: Seattle Sounders 0 - 1 Vancouver Whitecaps
ATT: 55,765
SEATTLE: Stefan Frei; Brad Evans, Chad Marshall, Jalil Anibaba (Andy Rose 82), Leo Gonzalez; Marco Pappa (Chad Barrett 62), Osvaldo Alonso, Micheal Azira (Gonzalo Pineda 65), Lamar Neagle; Clint Dempsey, Obafemi Martins [subs Not Used: Marcus Hahnemann, Kenny Cooper, Gonzalo Pineda, Zach Scott, Djimi Traore]
VANCOUVER: David Ousted; Steven Beitashour, Andy O'Brien, Kendall Waston, Jordan Harvey; Matias Laba, Russell Teibert, Mauro Rosales (Mehdi Ballouchy 71), Pedro Morales (Nicolas Mezquida 81), Kekuta Manneh (Kianz Froese 46); Erik Hurtado [subs Not Used: Paolo Tornaghi, Ethen Sampson, Sam Adekugbe, Johnny Leveron]