Robbie Russell kicked the decisive penalty as the underdog Real Salt Lake beat David Beckham and the star-studded Los Angeles Galaxy in a shoot-out Sunday night to secure their first Major League Soccer championship.

Real Salt Lake goalkeeper Nick Rimando made two saves during the shoot-out - after the score was locked at 1-1 following extra time - and Galaxy star Landon Donovan missed badly over the crossbar.

After Rimando smothered Edson Buddle's shot, Russell beat back-up Los Angeles goalkeeper Josh Saunders into the lower left corner to set off a wild celebration for a comeback win.

"It's nice to say we're the best team in the league," RSL coach Jason Kreis said. "... My honest opinion is we deserved to win that game."

Robbie Findley scored in the 64th minute to equalise at 1-1 after Mike Magee gave Los Angeles the lead in the 41st minute.

It was the second straight shoot-out victory for Salt Lake, which beat Chicago 5-4 on penalties last week in the Eastern Conference championship.

Rimando made three saves in the penalty shoot-out against Chicago and was at his best again in front of 46,011 fans on Sunday.

Beckham converted for Los Angeles to start the penalty kicks and the first four shots went to form.

Jovan Kirovski's shot was saved by Rimando, but Saunders followed by stopping RSL captain Kyle Beckerman.

Donovan, usually reliable from the spot for both the Galaxy and the US national team, then missed well over the crossbar, ripping off his captain's armband as he walked back to midfield, clearly disgusted with his shot.

Andy Williams had a chance to give RSL victory, but Saunders smothered his shot. Two rounds later, Williams was able to celebrate with Russell.

It was a stunning and disappointing conclusion for Los Angeles, which entered as a heavy favourite thanks to the star power of Donovan and Beckham.