It was not all smooth sailing for Real in the Western Conference semi-final, with the Timbers taking the lead in the 14th minute through Will Johnson's long-range free kick that dipped over the wall and deceived keeper Nick Rimando.
But Real forced an equaliser on 35 minutes as Chris Schuler headed home Javier Morales' corner to send the home fans wild.
Six minutes later Real had the lead when Robbie Findley collected Futty Danso's heavy touch and poked the ball past the keeper.
Leading 2-1 at half-time, Real struck another blow just after the break when Findley pulled the back for Devon Sandoval, who controlled and neatly finished in the bottom corner.
With the Timbers trying to limit the damage, Morales got his head to a Real corner and opposing keeper Donovan Ricketts could only help the ball into the net.
Portland was given hope in the 94th minute when substitute Frederic Piquionne headed Olmes Garcia's cross into the top corner.
The second leg will be played in Portland on November 24.
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