FC Dallas tumbled off the top spot in the Western Conference after being stunned 4-0 at home by the Vancouver Whitecaps on Saturday.
Bernie Ibini and Fredy Montero had already put the Whitecaps up 2-0 when Carlos Gruezo was sent off before the hour mark, and Montero soon added his second before Nicolas Mezquida also scored.
Australia international Ibini scored his first MLS score in the 18th minute with a bouncing shot from distance, and two minutes into the second half Kellyn Acosta conceded a controversial penalty that Montero converted to double the lead.