England midfielder Beckham helped Bruce Arena's side reach their first MLS Cup final since they won their second championship in 2005 as they beat the Houston Dynamo 2-0 with goals from Greg Berhalter and Landon Donovan in the Western Conference Championship.

Next Sunday's match at Seattle's Qwest Field against Eastern Conference champions Real Salt Lake was already a 36,000 sell out before the finalists were known.

However, the Galaxy's extra-time victory at the Home Depot Centre has prompted organisers to open up another tier of the stadium and make a further 6,000 tickets available.

Real Salt Lake, who finished fifth in the Western Conference at the end of the season to earn a wild-card berth for the play-offs, staged an upset to defeat the Chicago Fire on penalties following a goalless 120 minutes on Saturday night.

Againt Houston, Beckham sent in the free kick that led to Berhalter's 103rd-minute opening goal and the 34-year-old Englishman will now sign off for the MLS side in the American league's biggest game before heading to Italy on December 28 to start a loan spell with AC Milan.

Amid the celebrations following the Galaxy's hard-fought victory over Houston -

which marked a complete turnaround for the club which finished 2008 with the worst record in the league - both Beckham and Donovan emphasised there was still another hurdle to clear.

"We still haven't won anything," Beckham said. "We want to win next week but reaching it was the biggest thing. We've done that, done the hard work and this team deserves it."

Donovan's penalty in the second half of extra time was the USA international's MLS record-breaking 17th post-season goal, coming at the end of a game halted twice in regulation by floodlight failures.

"We're excited but we know we've got one more to go," Donovan said. "What a great game, couldn't ask for more, except for the lights going out but other than that it was a great night and now we go to Seattle next week."

Asked what had turned Galaxy from worst team in league last season into MLS Cup finalists, Donovan added: "Consistency and it starts with Bruce (Arena). Bruce has done a great job and our older guys have taken hold of what he's implemented and we've gone for it.

"We have a good team. We thought all year we had a chance if we got into the play-offs that we could do something special and now we've got one more to go."