So, you are feeling kind of guilty. You are a die-hard soccer fan, but you have been so busy following World Cup qualifying and matches from Europe that you have lost track of Major League Soccer. All of a sudden, it's playoff time, and you aren't quite sure what's going on.

Not to worry. We are here to help with this handy-dandy MLS Playoff Cheat Sheet.

Here we go . . .

1. Seattle Sounders vs. Houston Dynamo.

The playoffs kicked off Thursday night at Seattle's Qwest Field, site of the Nov. 22 MLS final, and, whoa, what a scene it was. A crowd of 35,807 -- the largest ever for a first-round MLS playoff game -- showed up ready to party.

The Sounders, the league's infant franchise, averaged 30,897 fans all season, about twice the average crowd of the rest of the teams. The passion surrounding the Seattle club is impressive (blue-and-green banners hanging from expressway overpasses). If only MLS could bottle that kind of enthusiasm and spread it around the league.

Game 1 ended in a scoreless deadlock, which was hardly surprising, considering these are the stingiest defenses in MLS, giving up 29 goals each all season. Both goalkeepers, Seattle's Kasey Keller and Houston's Pat Onstad, are rock-solid and accustomed to pressure. Keller has played in two World Cups and Onstad is a veteran of three MLS championship teams.

The match was extremely close -- 10 shots on goal for each team, 50-50 possession time, three yellow cards per team and eight corner kicks for Seattle to seven for Houston. It also was very physical and players nearly came to blows when Onstad knocked over Seattle forward Fredy Monntero.

``This is not rugby, it's still soccer,'' said Swedish star Freddie Ljungberg of the Sounders.

The two-leg series will be decided in Houston on Nov. 8. The Dynamo is going for its third title in four years, and has traditionally done well at home during the playoffs. Dynamo defender Ricardo Clark, forward Brian Ching and midfielder Stuart Holden have played for the U.S. national team and can handle the pressure of big games.

2. Los Angeles Galaxy vs. Chivas USA

The Southern California neighbors share a home stadium -- Home Depot Center -- and are bitter rivals. So much so that Chivas players, coaches and staff have grown playoff beards for the series, being dubbed ``Superclasico.''

Superstars David Beckham and Landon Donovan play for the Galaxy, which has a 10-3 edge in the series against Chivas. Despite the star power, the Galaxy failed to reach the playoffs the past three years, so this will be Beckham's first playoffs, and the first in three years for Donovan.

Coach Bruce Arena, a former U.S. national coach, has boosted the Galaxy's defense. The team allowed 31 goals this season, half of what it allowed last year, and the Galaxy finished the season strong.

Chivas will rely on Cuban forward Maykel Galindo and Sacha Kljestan, who has played for the U.S. national team. When Kljestan is on his game, Chivas plays better, and he is eager to redeem himself after a subpar season.

Game 1 is at 5 p.m. Sunday (ESPN2), and Game 2 is at 7:30 p.m. Nov. 8 (ESPN2).

3. Columbus Crew vs. Real Salt Lake

The defending champion Crew got off to a horrible start (0-2-5 in its first seven games), picked things up midsummer but slumped again at the end. The Crew lost three of its last four matches, all by shutout. The ageless Frankie Hejduk (yes, he's still around) will try to rile the Columbus troops, and Guillermo Barros Scheletto, last year's league MVP, will be counted on to come through.

Real Salt Lake has been tough to beat at home, but played poorly on the road, which bodes well for the Crew. Robbie Finley, Yura Movsisyan of Russia and Clint Mathis are the players to watch for Salt Lake. Miami Fusion fans will recognize Real Salt Lake goalkeeper Nick Rimando.

Game 1 is at 8 p.m. Thursday (ESPN2).

4. Chicago Fire vs. New England Revolution

In a season of parity -- none of the eight playoff teams won 50 percent or more of its matches -- the two least impressive teams left standing are the Fire (11-7-12) and Revolution (11-10-9). These clubs are quite familiar with each other, as they have faced each other in the playoffs five consecutive years and seven of the past eight. The Revolution knocked out the Fire three years in a row, and last year, the Fire came out on top.

The teams played twice this season, and tied both times, 1-1 and 0-0. The players to watch for the Fire are former U.S. national team forward Brian McBride and Mexican standout Cuauhtemoc Blanco. Shalrie Joseph leads the Revolution.

Game 1 is 2 p.m. Sunday (Fox Soccer Channel).