By Ridge Mahoney

There are pending rematches of MLS Cups past among the possibilities for this year’s edition, yet there’s also the chance of a debutant winner.

Houston and Los Angeles, which met in last year’s finale, have advanced. So has D.C. United, the four-time champion which among its MLS Cup scalps count a 1999 defeat of the Galaxy.

If you count Houston’s two victories before it moved from San Jose as well as triumphs in 2006 and 2007, those three teams have captured an impressive 11 of the 16 championship games contested since 1996. As the survivor with the worst record, Houston, cannot host MLS Cup, barring thunderstorms or hurricanes or other natural disasters that force a switch of venue. The pecking order is: 1. D.C. United (58 points), Seattle (56) and Los Angeles (54). Knocked out in the conference semis were the top seeds in the West (San Jose, 66 points) and East (Sporting Kansas City, 63), along with Real Salt Lake and New York, both of which finished with 57 points.

The November newbies, Seattle Sounders FC, exorcised the demons of three straight early playoff eliminations by edging past Real Salt Lake, 1-0, with their only goal scored against RSL in five – that’s right, five – meetings this year. They needed one of the sweetest strikes of this or of any season -- a humming half-volley hit by Mario Martinez -- to finally get something past a heroic Nick Rimando and reach their first conference final.

WILD WILD WEST. Going back into the regular season, RSL had blanked opponents for 513 consecutive minutes when the all-purpose, all-warrior Brad Evans pushed the ball upfield into the attacking third before squaring it to Fredy Montero. He took a touch and without looking, clipped it wide left, where Martinez surprised Rimando and probably most of the soccer universe by smashing a low whistler just inside the far post.

Martinez, one of the many Hondurans to join MLS in the past year and a half, hadn’t scored or started a game for the Sounders since signing in August. He landed a place in the starting lineup only because playmaker Mauro Rosales sat out with a bad hamstring. Within seconds of his strike, “Super Mario” references inundated the cyberworld. Does that make Seattle the team of destiny among this final four? It must get past the Galaxy to play in its first MLS Cup. And that won’t be easy, despite Seattle holding the supposed advantage of hosting the second leg. All four teams in that situation lost their conference semifinal series.

But if it can be done, Seattle coach Sigi Schmid could make history by winning an MLS Cup with a third team, following the Galaxy in 2002 and Columbus in 2008. He’ll need to beat another two-time winner, Galaxy head coach Bruce Arena, the architect of United’s titles in the league’s first two seasons.

In the aftermath of thumping Supporters’ Shield winner San Jose, 3-1, to win that series on aggregate, 3-2, Arena claimed the Galaxy has been the league’s best team since July. That point could be debated, but his players did believe that a 2-2 tie with the Quakes Oct. 21 – after 4-3 and 3-2 defeats – had boosted their confidence, and that confidence hadn’t wavered despite losing the first leg at home, 1-0, on a miserable mistake by keeper Josh Saunders.

Seattle played a solid defensive game to blunt the attack of RSL, which along with its sterling defensive record unfortunately hadn’t been rewarding it with goals. Centerbacks Jeff Parke and Jhon Kennedy Hurtado anchored a determined team effort; its next test will be the incisive attacking quartet of David Beckham, Landon Donovan, Robbie Keane, and Mr. Postseason, Mike Magee, who scored three playoff goals during L.A.’s MLS Cup run last year and netted what proved to be the series clincher against San Jose.

Rookie centerback Tommy Meyer played a commendable game to blunt the Quakes' attack for most of the match. The Sounders get one fewer day of rest and must travel to face the stay-at-home Galaxy Sunday (9 p.m. ET, ESPN) at Home Depot Center in the conference final, first leg. Schmid has to evaluate forward Eddie Johnson, who lasted the full 90 minutes coming off his own hamstring problems but didn’t look very dangerous. The coach does however, have a fit if not game-sharp Steve Zakuani to deploy during the series. Seattle lost at HDC, 1-0, less than two weeks ago on the final day of the regular season in the latest renewal of this unfriendly rivalry.

D.C. IS UNITED, NEW YORK ISN'T. Rafael Marquez is sent off, Kenny Cooper fails from the penalty spot with on a re-kick ordered because of encroachment, and the encroacher, Thierry Henry passes up a prime-location free kick in the final minutes. His proxy, defender Roy Miller, takes aim at a concession stand above and beyond the crossbar, and comes much closer to the former than the latter.

Thus the Red Bulls lose at home, 1-0, to a squad of storybook scrappers who preferred to slog through snow and slush Wednesday rather than wait a day to play the second leg they were supposed to host. Down to 10 men following the ejection of keeper Bill Hamid, United lived up to its name by scoring a dramatic winner through rookie Nick DeLeon to set up a conference final series against Houston.

This latest chapter in a soap-opera saga of disappointment and dysfunction should be set aside, for the two Eastern survivors are stirring stories in themselves. They start the Eastern Conference final series Sunday (4 p.m. ET, NBCSN) at BBVA Compass Arena.

Just as it did last year, Houston tweaked its roster by adding critical contributors: in this case, Honduran international Oscar Boniek Garcia and former Dynamo Ricardo Clark. But unlike last year, it had to take the wild-card route as the fifth-place Eastern finisher, and after beating Chicago, 2-1, on the road, took out SKC by the same score on aggregate.

It rode out a 1-0 loss in the second leg at Livestrong Sporting Park, surviving an astonishing 20-3 SKC edge in shots to conjure up nightmares of last year’s one-game conference final, a 2-0 Houston victory in the same venue. Thus for the second straight year SKC had won the conference title only to fall short in the playoffs.

United hosted the first leg against New York because of Hurricane Sandy, and overcame the frustration of a 1-1 tie at RFK to wait out a day’s storm delay to prevail at Red Bull Arena. It won’t have Hamid for the first leg, but keeper Joe Willis has filled in capably before and will be confident after a victory stemming from his save on Cooper’s second attempt. Plus, right now Coach Ben Olsen’s players believe they can beat anybody, anywhere, anytime. (Owner Will Chang’s minority stake in the World Series champion San Francisco Giants helps the karmic convergence.)

On experience, a large edge goes to Houston, which still has a few survivors from the title teams of 2006 and 2007 along with the 2011 finalist. Its attacking catalyst, midfielder Brad Davis, who goes all the way back to that first crown, is perhaps the sharpest and hungriest he’s ever been: he watched MLS Cup 2011 on crutches and with a torn quad.

United hasn’t been to the playoffs since the year of Houston's last title, to which there are links such as Dwayne De Rosario, the 2011 league MVP who proclaims he’s recovered sufficiently from an MCL sprain to rejoin the D.C. lineup. There’s another Dynamo-D.C. connection; United goalkeeping coach Pat Onstad manned the Houston nets in ’06 and ’07.

Along with a rematch of last year’s final there’s also a potential repeat of the classic inaugural MLS Cup; at Foxboro Stadium being lashed by a ‘noreaster, D.C. United rallied from a 2-0 deficit to stun the Galaxy, 3-2, in sudden-death overtime.

The 17th MLS season seems set for a classic ending. But the penultimate stage will write its own memorable chapter.