Jeff Cassar's Real Salt Lake scored twice in the first half for a 2-0 victory at home to the San Jose Earthquakes.
Ned Grabavoy and Sebastian Velasquez were on the scoresheet at Rio Tinto Stadium as the Western Conference's third-placed side secured a play-off place.
Grabavoy opened the scoring with a neat 25-yard effort, side-footing into the bottom corner through a crowded penalty area.
Velasquez kneed in a corner in the 29th minute and that would be all Real Salt Lake needed against the struggling Earthquakes.
The Columbus Crew remain on track for the play-offs after a stunning 3-2 victory at the Philadelphia Union.
Daniel Cruz and Andrew Wenger appeared to have the Union in complete control, with the latter's goal coming in the 75th minute.
But it was all the Crew, fifth in the Eastern Conference, from then on.
Ethan Finlay tapped in a cross to pull the first back before Justin Meram levelled just a minute later when he tucked away a finish after a fine individual run.
Jairo Arrieta got in front of his marker to put away a cross, giving the Crew a victory that appeared unlikely eight minutes earlier.
Bradley Wright-Phillips scored his 25th league goal of the season as the New York Red Bulls beat Toronto 3-1.
Chivas USA came from behind to overcome the Colorado Rapids 2-1 and Marco Di Vaio netted a brace as the Montreal Impact drew 2-2 against the New England Revolution.
