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Reigning MLS Cup champions Seattle crushed Dallas 4-0 to climb into third place in the Western Conference.

The Timbers beat DC United 4-0 to also secure a spot from the west, while Houston Dynamo and Sporting Kansas City also clinched play-off places.

In Seattle, the Sounders took a 31st-minute lead through Victor Rodriguez, who finished clinically after being put in by Clint Dempsey.

A quick-fire brace from Will Bruin helped Seattle on their way, the forward putting away a rebound and later a side-footed finish.

Lamar Neagle headed in a Nicolas Lodeiro cross to complete the comfortable win in additional time.

Portland cruised past DC thanks to a second-half brace from Sebastian Blanco at Providence Park.

Diego Valeri scored with a penalty before Alvas Powell curled in a fine effort shortly after half-time.

Blanco made it 3-0 with a curling strike into the top corner on the hour-mark before he sealed the victory.

Sporting and Houston are also heading to the play-offs after playing out a 0-0 draw.

Western Conference leaders Vancouver Whitecaps were held to a 1-1 draw by San Jose Earthquakes, who are fighting for the sixth and final spot.

The sixth-placed Earthquakes are level on points with seventh-placed Dallas, while Real Salt Lake are a point back after going down 1-0 to Colorado Rapids.

The Eastern Conference play-off spots were already secured, with leader Toronto edging Montreal Impact 1-0.

New York City went down to New England Revolution 2-1, while Nemanja Nikolic pulled clear atop the goalscoring charts with a hat-trick in Chicago Fire's 3-2 win over Philadelphia Union.

Elsewhere, the New York Red Bulls drew 0-0 with Atlanta United, Orlando City lost 1-0 to Columbus Crew in Kaka's final home game for the club and LA Galaxy powered past Minnesota United 3-0.