Donovan, Beckham score in Galaxy win
Juninho scored the go-ahead goal in the 83rd minute for the defending champion Galaxy, who had struggled in the season's early going.
Kris Boyd scored goal for Portland, which lost its fourth straight.
Juninho broke a deadlock when he won a loose ball outside the box. The Brazilian unleashed a strike from 23 yards out that never got more than a few inches off the ground and nestled into the left corner of the net.
Beckham followed it with his first goal of the season, from long range, and then went sliding into the corner area to celebrate.