Alan Gordon has now scored in the last minute of regulation or later for three games running, the latest toppling his former club.
But for the late drama, the story of this game would have been Hector Jimenez. In his third career start, the midfielder scored within three minutes. Juninho's penetrating low ball was flicked backwards by Chad Barrett, and Jimenez tucked it away.
The 23-year-old then got himself sent off an hour into the match. He chased his own heavy touch and lunged in two-footed at Steven Beitashour.
The Galaxy thought they'd done enough to preserve a win even down a man when, with less than 20 minutes to go, Mike Magee rolled past a defender and goalkeeper Jon Busch to put LA two goals up. But a few minutes later Steven Lenhart's diving header finished a Marvin Chavez corner to start the comeback.
A Chavez cross instigated the equalizer as well. David Beckham's arm got in the way of a blasted shot, and Khari Stephenson put away the penalty kick.
Former Galaxy forward Alan Gordon scored the winner deep in stoppage time. Los Angeles didn't deal with a ball lugged into the box, allowing it to bounce. Gordon had no such hesitation, heading the ball past Brian Perk for his third late goal in as many games.
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