1st leg: Saturday, Nov. 9 -- 2:30 p.m. ET
2nd leg: Saturday, Nov. 23 -- 7:30 p.m. ET
How they got here: Sporting Kansas City
After going down 2-0 to New England in the first leg of the Eastern Conference semifinal, Aurelien Collin took it upon himself to drag SKC back into a tie.
First, the French defender halved the deficit at Gillette Stadium and then, in the first half of the second leg, leveled the tie.
Dmitry Imbongo restored the Revs' advantage before local boy, Seth Sinovic, scored against his former club to force extra time, during which the home team's class eventually showed.
With penalties looming, Claudio Bieler pounced on a cross from ex-Revolution midfielder Benny Feilhaber to prove just why he is paid the designated player big bucks.
How they got here: Houston Dynamo
Dominic Kinnear's team also trailed by two goals in the first leg, as New York took control. However, a resurgent second half display saw the Dynamo draw level and finish the game a man up after Jamison Olave was shown a straight red card for a reckless challenge.
The absence of the Colombian gave Houston extra hope going into the return leg, but the Red Bulls took the aggregate lead again after Tally Hall gifted Bradley Wright-Philips the opener.
Hall, though, made amends with a string of fantastic saves to keep his team in the game and Houston drew level when Brad Davis pounced a mistake from Ibrahim Sekagya.
Just like Kansas City, Houston won the series in extra time when Omar Cummings, who had scored in the first leg, saw his effort creep over the line to complete the upset of the Supporters' Shield winners.
Goals were at a premium, with the two teams combining for only three in as many matchups.
That man Collin made the difference to earn SKC a road win on May 12 before a 1-1 draw followed two weeks later. Kei Kamara, now of Middlesbrough, saved a point for Peter Vermes' team after Davis had opened the scoring.
The last regular-season clash came exactly one month ago. Houston dominated at home in terms of shots on goal, but the game finished scoreless.
Key matchup: Brad Davis versus Chance Myers
Cummings grabbed the headlines against New York, but extra time would not have been possible had it not been for Davis' equalizer. The contrast of styles between Davis and Oscar Boniek Garcia sees them complement each another to give Houston good balance on the flanks.
The partnership forged by Collin and Matt Besler is vital to Sporting, as are the team's full-backs and it is they who will come under the most scrutiny during this series. Strikers need service and if Sinovic and Myers can restrict the output from Houston's wide positions, they will go a long way to helping win the two-leg series.
Surprisingly, they may achieve that by attacking rather than defending. With Corey Ashe set to miss the first leg through suspension, Sporting should attempt to pin back their opponents and force Davis to spend more time in the defensive third rather than the offensive one.
That could prove difficult if Houston look to press high in the same way it did against New York. However, one thing Vermes will have noted from the second leg of that series was how susceptible the Dynamo were from wide positions themselves, particularly in the first half.
The Red Bulls were repeatedly able to get the outside Houston's full-backs and if it wasn't for poor finishing, the series could have been put to bed before Kinnear's men fought back.
X-factors: Midfield maestros
For Houston it's hard to look past Davis. The piano player in a midfield full of piano carriers, he has been central to so much of their success for so long and his creativity unsurprisingly puts him atop of the team's assist chart. His pass completion rate is 84 percent for the season and, according to whoscored.com, he averages at least two key passes a game.
Meanwhile for Sporting KC, the mantle of potential game winner falls on Graham Zusi. Blessed with a dangerous delivery, he will be a key man if his teammates are to make the most of their opportunities from set plays and take advantage of a Houston back line that has seemed to struggle with physical opposition of late.
Zusi also benefits from having creative players around him, especially Feilhaber, whose presence should help ease the pressure on the United States' midfielder.
Prediction: Kansas City
Houston was far from fancied by many (myself included!) against New York, but Kinnear used all of his playoff experience to mastermind an impressive comeback victory.
However, looking at this logically, I can't see another Dynamo upset. They go into the first leg at BBVA Compass Stadium on the back of a draining game and it remains to be seen how much that fightback took out of them.
Sporting is unlikely to be as wasteful in front of goal as New York was, especially now that Bieler has ended his scoring drought. The fact Vermes' team took five points from Houston in the regular season also gives credence to the idea SKC is the favorite, although the Dynamo have a great record at home against Sporting.
I see a tight affair in Texas before a home win at Sporting Park puts Vermes and Co. into MLS Cup 2013.