Keane's goal in the 68th minute, after he beat an injured but game Jamison Olave, put the finishing touches on a game that was as entertaining for those watching as it was frustrating for RSL.
"It seemed from the get-go there were chances to be had," RSL midfielder Kyle Beckerman said. "It could be because it was late in the season, with back-to-back games, it could have had an effect.
"It was a game of storms, really."
In the second half, RSL forward Fabian Espindola had two clear chances at goal. He hit the post on the first effort seconds after Los Angeles' second goal, a header by Mike Magee from a beautifully bending Beckham service. Then, six minutes after Keane's goal, he whiffed a chance inside the 6-yard box.
"I was saying, 'Go in, go in, please go in'; it just hit the post, so ... " said Espindola. "I tried to hit it right, and I didn't. They had a great night. It was even in the first half. They challenged us ... so they had a great night. Good for them."
Sunday night's game was a microcosm of RSL's season: Moments of brilliance were followed by disastrous mistakes. And the Galaxy were too good not to eventually make Salt Lake pay especially at the end when RSL had to attack, leaving gobs of open space for counterattacks.
The Galaxy's Landon Donovan, who was really not much of a factor for much of the game, put LA in front with a penalty kick in the 22nd minute. RSL midfielder Andy Williams barged into Omar Gonzalez inside the 18-yard box and referee Jorge Gonzalez wasted no time in pointing to the PK spot.
However, RSL evened things just three minutes later when Olave headed to Alvaro Saborio, who shot the ball by Galaxy goalkeeper Josh Saunders in a half that was about as even as the 1-1 score.
In fact, the first 45 minutes could have been called a half of missed opportunities by both sides. Each team had five shots at goal, with two on target.
Keane and Beckerman banged shots off the post Beckerman's in extra time as RSL attacked with a fury to finish the half. Meanwhile Keane unveiled a bit of his Irish magic as he nearly scored in the 33rd minute on a beautifully bending shot that just went wide.
"You can't give a player like that kind of time and space on the ball," RSL coach Jason Kreis said. "He'll punish you."
Earlier, an unmarked Chris Schuler, near the 6-yard box, sent a header spinning wide left.
"They were a little sharper than us," RSL midfielder Will Johnson said. "We were fighting, battling, but they had the best big-time plays."
Rimando found himself defending cross after cross by Beckham. Saunders' reaction save in the sixth minute stonewalled a point-blank shot by Robbie Russell on an RSL corner kick.
Even though Real owned the ball 53 percent of the time, it had problems solving the Galaxy's midfield defense. Each RSL rush eventually lost steam at midfield. It then had to rely on its back four to turn away strong LA attacks.
The Galaxy began opening up giant holes in the RSL midfield, allowing for Beckham to operate out of large areas of space. Chad Barrett nearly scored midway through the second half, only to bash the ball into RSL defender Will Johnson's face. Magee then headed another spectacular cross by Beckham over the cross bar.