A brace from Giovani dos Santos helped the Galaxy record a 4-2 win over the Earthquakes in San Jose.
It extended the Galaxy's unbeaten run to five matches as they rose to sixth in the Western Conference.
Chris Wondolowski had put the Earthquakes ahead in the California Clasico with a finish at the back post in the 10th minute.
Joao Pedro leveled for the Galaxy before Dos Santos' first, which came via the penalty spot.
Danny Hoesen then equalized for San Jose with a close-range finish and the entertaining half came to an end when the visitors went ahead again thanks to a Victor Bernardez own goal.
A Dos Santos header – his fifth goal in four games – sealed the win for the Galaxy.
Elsewhere, Western Conference leader Sporting KC went down 1-0 to the Colorado Rapids.
Kortne Ford's 11th-minute goal proved decisive for Colorado, which is bottom of the conference, before Sporting had Roger Espinoza sent off late.
Lamar Neagle's penalty helped DC United to a 1-0 win over the Vancouver Whitecaps, who had Cristian Techera hit the post with a 96th-minute spot kick.