Los Angeles - South Korean international Hwang In-beom scored the only goal as the Vancouver Whitecaps sent league leaders Los Angeles FC crashing to their first defeat of the season on Thursday.
Hwang, who made his Major League Soccer debut for Vancouver last month, rammed home a rebound in the 27th minute after winger Victory Giro's effort cannoned back off the woodwork.
The goal handed Vancouver their first win of the season and saw them move up to ninth place in the Western Conference standings with five points from seven games.
LAFC remain top of the Western Conference, with 19 points from eight games, three points clear of Seattle in second place.
Seattle however have two games in hand over Los Angeles.