As Major League Soccer enters yet another full week of action in the 2012 season, it makes way for the Atlantic Cup, whose origins go back all the way to the inaugural 1996 season.

The Atlantic Cup is the name given to the D.C. United and New York Red Bulls' bitter rivalry as well as the trophy the winning team receives.

This year's edition kicks off this Sunday, when New York travels to the nation's capital for its first of three matches. Due to the proximity of both clubs, and maybe even some jealousy between them, year after year this rivalry has given fans the opportunity to see amazing soccer. 

If this Sunday's match reaches tradition's expectations and becomes another MLS classic, these will be six reasons why.

1. Winning Team Will Take Advantage of the Opposition's Setbacks

Coming into this Sunday's match, NYRB will be without the services of center-back Wilman Conde, who will be out for a month due to a groin injury. Without his presence in the back line, the Red Bulls have been very vulnerable.

New York has also lost Rafael Marquez after MLS suspended him for three games due to his foul on San Jose's Shea Salinas, who suffered a broken clavicle. 

On the other hand, D.C. United will already be tired from its mid-week against the Montreal Impact, which it tied 1-1. D.C. didn't have to travel, hosting the match at RFK Stadium, but the come-from-behind draw took a lot of energy out of the squad. 

Watch for D.C. United head coach Ben Olsen to make some lineup changes and start fresh legs against a well-rested New York squad. 

2. Both Teams Will Vent out Frustrations

Like I mentioned earlier, part of Conde's being absent from NYRB's defense is that it makes it susceptible to attacks. The most recent example was its 2-2 draw against the San Jose Earthquakes.

This was a very anticipated game last week because it boasted the second-place teams of each conference. But the Red Bulls must have believed that they deserved the three points after going on top in the scoring sheet twice, and at home, only to allow the lead slip away due to defensive mistakes. 

Now for D.C., their 2-1 victory at New England was a huge confidence booster, but the team's draw against visiting expansion side Montreal may have dampened that a bit.

So both these teams will approach Sunday with frustration on their minds, which only three points will relieve.  

3. The Dwayne De Rosario Factor

These two squads exchanged wins last season. NYRB defeated D.C. at RFK with a 4-0 spanking, while United returned the favor at Red Bull Arena later in the season, winning 1-0.

The twist is that United's goalscorer for the win against New York was Dwayne De Rosario, who had just weeks prior, joined D.C. from the Red Bulls after he wasn't able to perform for the club. 

Of course, New York got the last laugh as it barely made the playoffs while D.C. once again looked in from the outside. But the loss to United and the goal by the former Red Bulls player, at New York's house no less, has left a sour note within the Red Bulls franchise.

Also, De Rosario went on to win league MVP and the Golden Boot from the numbers he put up with D.C.—numbers that New York could have used in the playoffs before it crashed out against eventual champions LA Galaxy.

The Red Bulls will want to seek some type of revenge, and with De Rosario currently a bit out of form, the perfect time to strike would be this weekend.

4. Most of the League's Heavy Hitters Will Be on the Field

In theory, both of these squads boast some of the best offensive players in the league. In practice, only one team has been able to display it.

D.C. United has the aforementioned reigning MVP De Rosario, as well as Albanian Designated Player Hamdi Salihi. However, neither have been able to find the back of the net. The team's other forward, Maicon Santos, has been the relief, scoring four goals this season. 

Now the Red Bulls are a different story. Thierry Henry has killed, scoring seven goals and five assists. And his current partner in crime, Kenny Cooper, has also scored seven goals. This tandem has become the most lethal in Major League Soccer.

That doesn't mean that we can disregard United's attacking players. They have shown the league what they are capable of with a 4-1 whooping of FC Dallas and the recent 2-1 come-from-behind victory against the New England Revolution.

With all this talent on the field, and after you sprinkle in some Chris Pontius, Nick De Leon, Danny Cruz, Dane Richards, Joel Lindpere and Jan Gunnar Solli, something explosive will happen.

5. D.C. United Leads the Rivalry

Since 1996, D.C. has led New York 44-25-8 in all competitions. But since the Red Bulls era, that margin has been kept to 8-4-5 in favor of United.

It's not a terrible record for the Red Bulls, but with the talent now at the team's disposal, and with three Atlantic Cup games to be played this season, New York will want to close that gap in the rivalry.

Also, D.C. United is currently in third place in the Eastern Conference, only one point behind New York. A win on Sunday will leapfrog the Red Bulls to second place, which will definitely be on the mind of some of United's players.

It's guaranteed the game will not be very friendly, and the referee will have a tough time setting the tone to keep all 22 players in check.

6. National Broadcast

This match will have an additional feel of importance, especially for fans, since it will be aired nationally on ESPN2. 

In addition, with D.C. hosting it will be played in the confines of RFK Stadium, which can be a fortress for United. Last year's game at RFK brought in over 18,000 fans, so expect a great atmosphere as the bleachers will be bouncing once again.  

As of late, RFK hasn't been the bunker it used to be in the 1990s and early 2000s. Nevertheless, if the fans show up—which they will, and from both sides—the environment in that stadium will erupt like it hasn't in a long time.

D.C. United/New York Red Bulls will kick off at 6:00 pm EDT on ESPN2. 

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