When it comes to men's tennis, the power structure is made up of four men above all else. Novak Djokovic, Roger Federer, Andy Murray and Rafael Nadal have dominated the past decade, each owning multiple Grand Slam event victories.
The question is, which contenders have the best chance of unseating the big four at the 2013 U.S. Open?
Since Marat Safin won the 2005 Australian Open, Djokovic, Federer, Murray and Nadal have won 33 of the past 34 Grand Slam events. The last time someone other than the big four broke through was at the 2009 U.S. Open.
Four years later, the rest of the world looks to break through.
The reign these four men have experienced is unlike anything we've ever seen in the history of the sport. Even during the golden age of American tennis, when Andre Agassi, Jim Courier and Pete Sampras dominated, players were able to break through.
The question is, who can end the reign of terror in New York during the 2013 season?
Tomas Berdych, Czech Republic
ATP Rank: No. 5
Best U.S. Open Result: SF (2012)
Tomas Berdych is getting hot at the right time, defeating Murray, Jarkko Nieminen and Tommy Robredo en route to the semifinals of the Western & Southern Open. Berdych eventually lost 5-7, 6-7 to Nadal, still displaying his borderline elite ability.
Still, it's clear that Berdych is a legitimate contender.
Berdych made a semifinals appearance at the 2012 U.S. Open, upsetting Federer in five sets in the quarterfinals. In 2013, he has quarterfinals appearances at the Australian Open and Wimbledon, reminding us of how lethal a player he can be.
Keep in mind, Berdych reached the finals at the 2010 Wimbledon.
Berdych, a 6'5" powerhouse, is as good as anyone in the world when on his game, but consistency is the issue.. he's been criticized for his mental make-up during big matches, and in New York, his ability to push through will be tested.
With a powerful forehand that gets even the best in the world off-balance, the talent is there. Look for Berdych to remind the world of that by making a run through the field and contending for the title.
Juan Martin del Potro, Argentina
ATP Rank: No. 6
Best U.S. Open Result: W (2009)
As previously alluded to, no one other than the Big Four has won a Grand Slam since the 2009 U.S. Open. The player who won that event was Argentinian star Juan Martin del Potro.
Four years later, del Potro is only 24 years old and primed to break through with a second career Grand Slam title.
Del Potro has reached the quarterfinals in four of his past six Grand Slam events, reaching the semifinals at the 2013 Wimbledon. In his most recent tournament, del Potro reached the semifinals at the Western & Southern Open, losing an instant classic to John Isner.
Two weeks prior, del Potro built upon his Wimbledon success by winning the ATP Citi Open.
No one in their right mind will question whether or not del Potro has the ability to join the big four as one of the world's best. What is uncertain, however, is whether or not he can remain healthy and continue inching closer to a second Grand Slam.
With del Potro experiencing full health and playing at an extraordinary level in August, expect him to be a legitimate contender in New York.
David Ferrer, Spain
ATP Rank: No. 4
Best U.S. Open Result: SF (2012)
David Ferrer hasn't played very well in August, losing in the second round of the Rogers Cup and third round at the Western & Southern Open. With that being said, Ferrer has been the best player in the world outside of the big four over the past two years.
He's reached the quarterfinals in each of the past seven Grand Slam events.
Ferrer nearly broke through, reaching the finals of the 2013 French Open, but was forced to play Rafa Nadal. Fortunately, Ferrer also broke through at the 2012 U.S. Open, getting out of the fourth round for the first time at the event.
It took four sets for Djokovic to take Ferrer down in the semifinals.
If there is any player worthy of joining the big four as the best players in the world, it's Ferrer. He's far ahead of the rest of the world when it comes to recent Grand Slam events, displaying inspiring endurance at the age of 31.
If he's ever going to break through, and he certainly has the ability to do so, Ferrer will do it at the 2013 U.S. Open.