The Earthquakes started the weekend with the fewest goals allowed in the MLS (26) but conceded as many as four in a regular-season match for the first time since May 13, 2000. The loss dropped the defending MLS Cup champions to 2-9-2 on the road.
Defender Ryan Nelsen scored in the 74th minute to lift United into a 2-2 tie. A centering cross from Petter Villegas, flicked on by Eddie Pope, found Nelsen six yards from the goal line and he knocked home the close-range shot for his fourth goal of the season.
Pope got the game-winner 10 minutes later, heading home Marco Etcheverry's corner kick for his first goal of the year.
Villegas added an insurance goal two minutes later. Jaime Moreno made another penetrating run toward the penalty area, feeding an overlapping Villegas on the right side of the box. The native of Ecuador used a first touch to score his second goal of the campaign.
United grabbed the lead just before halftime when midfielder Bobby Convey was the beneficiary of a trademark run by Moreno. He spotted Convey near the top of the penalty area and the 19-year-old midfielder calmly controlled the offering before launching a low shot inside the right goalpost and past goalkeeper Jon Conway.
After the break, Earthquakes forward Landon Donovan scored twice in 10 minutes to erase a 1-0 deficit.
Richard Mulrooney fed Donovan on the left flank and the striker went head-to-head against his U.S. World Cup teammate Pope and cut inside, rifling a low line drive inside the near post.
Donovan's second goal came on a give-and-go with Manny Lagos. Donovan ran onto the return feed at the top of the box, beating two defenders and depositing the ball into the back of the net.
Nick Rimando made seven saves, including several spectacular stops, to keep United in the game. He blocked point-blank shots by Jimmy Conrad in the 80th minute and Ian Russell in the 82nd and 90th minute.
United pulled within six points of the MetroStars for the final playoff spot.