A late goal from Ned Grabavoy was enough to give RSL a win, and to keep Portland's terrible start to the season going.
Real Salt Lake got 78th-minute goal from Ned Grabavoy to claim a win over Caleb Porter's side, with Grabavoy picking up a pass through the center channel and rushing past Darlington Nagbe before finishing well with his left foot into the far post.
Maximiliano Urruti had the best chance to put the Timbers in front before the goal, pushing his shot wide of the mark on the hour mark after being gifted a chance by a bad giveaway from RSL.
Javier Morales managed to slide one off the post in the 73rd after picking up a pass just around the penalty spot and slipping his shot past Donovan Ricketts.
The loss leaves Portland second to last in the Western Conference, just one point up on San Jose with the Earthquakes holding two games in hand, while RSL remains unbeaten on the year and sits comfortably in second place out West.