On the decisive goal, Eddie Johnson connected with Alonso on a perfect crossing pass and the Cuban player booted a spectacular running shot into the net for his first goal of the season.
The game-winner came after the two clubs had combined for the quickest two goals to open an MLS game since 2007.
Johnson scored just 80 seconds into the game for Seattle (9-5-7), and Drew Moore answered with a goal for the Rapids in the 3rd minute.
Colorado (7-14-1) tied a club record with its sixth straight loss.
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