Rimando made six top draw saves in the rain in Portland and watched a number of other shots flash wide of his goal, as the Timbers were forced to settle for a scoreless draw in the penultimate round of the regular season, significantly weakening their bid to qualify for the play-offs.
It was a game for the men in goal with Donovan Ricketts also making three top saves for the Timbers.
Portland dominated at Providence Park - particularly in the second half - but whenever they got a shot on target, Rimando or one of the United States international keeper's team-mates denied the home side a crucial goal.
Rimando's best save came in the 61st minute.
Soon after, RSL's Luis Gil blocked Portland defender Norberto Paparatto's header from a corner on the line.
But it was Portland that made all the running to finish the contest as visiting defenders made a number of desperate blocks, before the Timbers' Maxi Urruti hooked a cross across the face of goal - and just out of reach of any team-mates - in second-half stoppage time for the final decent chance.
The Whitecaps will play two teams outside the West's top five to finish the regular season - San Jose and seventh-placed Colorado Rapids.
