A fantastic volley from Erick Torres and a red card for Real Salt Lake doomed the Western Conference's third-place side to a loss.
Luke Mulholland was sent off inside the opening 10 minutes for a high studs-up tackle, leaving RSL with 10 men for over 80 minutes.
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Torres put his team in front in the 35th with a glorious strike on a Tony Lochhead pass, taking it on the full volley and lashing home to make it 1-0 for the home side.
The win was just the third of the season for Chivas USA, with the loss marking just the third defeat for RSL this season.