The Argentine playmaker scored the first two goals and picked up an assist as his side humbled the Western Conference laggard.
Valeri got his night started off with a goal in the 16th minute. Teammate Jose Adolfo Valencia was dispossessed by the Chivas defense inside the box, but the ball only fell as far as the Argentine, who was quick to zip it in and give his team the lead.
The Argentine did his thing again in the 29th. A poorly placed Jaime Frias pass fell right to Valeri, who confidently dribbled into the Goats back line and chipped Tim Melia from 20 yards.
Valeri switched from killer to creator to set up the third goal. Taking a long pass from Futty Danso, Valeri held off Josue Soto and turned him, leaving the defender on his backside. Valeri then rifled a pass through the legs of Carlos Bocanegra to meet the near-post run of Rodney Wallce, who hit a first-time shot into the net.
It wasn't until the 72nd minute that the Timbers scored a goal that wasn't assisted or finished by Valeri. This time, Ryan Johnson scored after Melia denied Wallace's initial attempt on target.
Will Johnson completed the rout in the 76th minute, curling a free kick around the wall and into the far corner, despite Melia putting a hand to it.
Portland (14-5-15) finishes the 2013 regular season atop the Western Conference standings, while Chivas USA (6-20-8) is at the foot of the board.