Both teams will look to get back in the win column and improve their Western Conference positions.
The host won that encounter and has continued to display championship form this season, taking its first loss of the season to the Seattle Sounders on Saturday and coming into this weekend's contest after a 1-1 midweek draw with Columbus.
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Portland has had a more difficult time replicating last season's form and currently sits in the penultimate position in the Western Conference. A six-match unbeaten streak had Caleb Porter's men looking stronger, but a 4-3 loss to Vancouver last time out has dampened spirits.
RSL will be without midfielder Kyle Beckerman and goalkeeper Nick Rimando, who are with the United States on international duty. Alvaro Saborio, a forward who was set to go to the World Cup with Costa Rica, is also unavailable after sustaining a foot injury. Portland fullback Michael Harrington may return from a right ankle injury.