New signing Chabala, formerly of Houston Dynamo, opened the scoring in the 26th minute when he received a clever ball from Darlington Nagbe and hammered home from just inside the area, much to the delight of the JELD-WEN Field crowd.
Perlaza added a second just after the half-hour mark when Diego Chara’s touch found him at the top of the box and he finished low and hard past Josh Saunders before Brunner wrapped it up in the 68th minute when he powerfully headed home Sal Zizzo’s corner.
The win was Portland’s seventh of the season and kept them in seventh place in the West whilst inflicting the first defeat on the Galaxy in 14 league matches.
Veljko Paunovic netted first for the Union with a blistering left-footed shot from 20 yards in the 34th minute before Pardo struck back 20 minutes later with a superb finish from the edge of the area.
And in the other game, Sporting Kansas City scored twice in the first half to defeat Real Salt Lake 2-0 despite losing goalscorer Roger Espinoza to a red card prior to the hour-mark.
Sporting Kansas City: 2 (Roger Espinoza 30’, Teal Bunbury 35’, red card: Espinoza 57’)
Real Salt Lake: 0
LIVESTRONG Sporting Park, Kansas City, KS – 18,467