From the beginning, Salt Lake seemed out of sorts, trading its usual possession-heavy style in favor of quick counterattack opportunities against the Galaxy, while L.A. provided most of the offense.
Still, it was RSL that broke through back-and-forth deadlock first.
In the 53rd minute, defender Nat Borchers found Ned Grabavoy at the top of the 18-yard box. The midfielder laid off the ball with a brilliant flick to spring Joao Plata, who beat Galaxy goalkeeper Jaime Penedo.
The lead, however, did not last long.
RSL made critical tackles when they were needed in the first half to keep the game scoreless, but eventually the Galaxy were able to break through.
"I think you have to feel that if you're going to have to do that all night, at some point it's going to give and it gave for sure in the second half," Kreis said.
L.A. forward Robbie Keane cut back against a sliding Carlos Salcedo and found the right corner of the netting for an equalizing goal in the 57th minute. A minute later, Salt Lake defender Chris Wingert kept the Galaxy from going ahead when he chested a Landon Donovan shot headed off the line.
But the defender's heroics would not be enough to save his team.
Keane side-footed a shot by Nick Rimando in the 67th minute to give L.A. the lead.
Defender Omar Gonzalez, just days removed from the announcement of his new Designated Player contract, snapped his head on a Landon Donovan corner kick in the 75th. And Keane iced the game with a chip shot over Rimando to complete his hat trick, a performance that came just a week after Donovan scored three goals of his own against Dallas.
RSL's Robbie Findley tapped in a stoppage time goal to help make the scoreline look less lopsided.
The loss snapped a streak of five straight wins for RSL in the former Home Depot Center. Salt Lake had beaten Chivas three times and the Galaxy twice in Carson by a combined score of 16-3 coming into the game.
"They were the better team. They got the better chances. They looked fresh, sharp and we weren't that," Rimando said. "It's humbling. It's humbling to get beat like that. ... They were the past champions for a reason, so it's good to go against these guys and see where we're at and know that next time we've got to be better."
RSL won't get much to languish in the memory of the performance. The team heads to Portland for a midweek matchup with a Timbers team that gave RSL plenty of trouble despite losing 2-0 in Open Cup semifinal play earlier this year.
Portland captain, and former RSL midfielder, Will Johnson did not practice with this week and was held out of the Timbers' lineup for Saturday night's game against FC Dallas after being injured in his Rio Tinto homecoming.
Salt Lake, meanwhile, will be without the services of captain Kyle Beckerman, who picked up a yellow card during Saturday's loss that will keep him out of the match due to accumulation.
With nine games remaining in the season, RSL's 41 points are now just two clear of Sporting Kansas City, the New York Red Bulls and the surging Colorado Rapids.
Sporting could overtake RSL for the league's top spot with a win Sunday night against San Jose.
Storylines Keane leads L.A. to victory
R Los Angeles' Robbie Keane scores a hat trick as the Galaxy beat RSL 4-2.
• Salt Lake's Joao Plata scores in the 53rd minute for a 1-0 lead.
• With the loss, Real Salt Lake's margin atop the MLS standings is now two points.