The Galaxy captain turned in a top-class showing to overwhelm a Philadelphia side that had the upper hand for much of the match.
Los Angeles went on the scoreboard early. Landon Donovan swung in a corner and Zac MacMath whiffed his catch. The ball bounced off his face and into the net to give LA a fluke lead in the third minute.
The Union equalized in the 23rd minute. Amobi Okugo snuck into the penalty area and stuck his head on Sheanon Williams' long throw.
LA re-took the lead in the 71st minute. Robbie Keane was slipped through the defense by Landon Donovan, and the Irishman had an easy point-blank finish to make it 2-1.
The Galaxy killed the game off just a few minutes later. Donovan picked out Hector Jimenez cutting in unmarked from the right flank, and the midfielder had a straightforward task to put his shot inside MacMath's far post.
Donovan turned the screws a bit more in the 87th, making it 4-1 when he was left unmarked for Robbie Keane to pick out on the run.