With the score tied 1-1 in the 84th minute, Garcia outran the defense to get open and headed a cross from Javier Morales into the net for the decisive score.
He capped another long run with an insurance goal on a breakaway 2 minutes into stoppage time and Khari Stephenson also tallied as Salt Lake (8-5-3) strengthened its hold on second place in the Western Conference with 27 points.
Landon Donovan netted the only goal for the Galaxy (6-6-5).
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