The Canadian side takes a commanding lead in the Cascadia Cup and bolsters its playoff hopes with a win over high-flying Seattle.
The MLS-leading Sounders were down Gonzalo Pineda and Osvaldo Alonso with suspensions, while Obafemi Martins was ruled out injured and returning World Cup stars Clint Dempsey and DeAndre Yedlin were not included in the squad.
Fernandez scored the game's only goal in the 12th minute, but it was well worth the price of admission. Given ample space by the Sounders defenders, he teed up from almost 30 yards and lashed one in past Stefan Frei.
Erik Hurtado spurned a great chance to put the hosts out of reach, sprinting ahead of the Seattle defense on a breakaway only to make his shot simple for Frei to deal with.
Frei came up with a few decent stops to keep his team in the game, but Seattle was unable to find its equalizer.
The win gives the fifth-place Vhitecaps (6-3-7) a four-point cushion over LA and Portland in the Western Conference playoff race, although the Galaxy have a pair of games in hand. Seattle still enjoys a seven-point lead over RSL at the top of the conference, and the same margin above RSL and D.C. United for overall command of the league table.