Winning a tennis match at a high level is extremely impressive; playing fifty-something matches while only suffering two losses borders on supernatural absurdity.
After winning 43 consecutive matches—including multiple wins over Roger Federer and Rafael Nadal—Novak Djokovic's ridiculous streak was snapped at Roland Garros. Despite that loss, he continued to massacre everybody that got in his way.
His several wins include the Australian Open, Wimbledon and seven other tournaments, in which he beat many highly ranked players.
In 2010, he was not really considered a major grand slam contender. His serve was a liability—last year he had more double faults than aces—he was not consistent at all and he was prone to breathlessness and tiredness as the drop of a hat.
However, going into 2011, Djokovic obviously worked like a dog, got his confidence up and most importantly, went on a gluten-free diet (which helped the tiredness). He has now started pounding the ball off of both flanks, serving like a monster, volleying very well and moving well.
This has taken his game to the next level; he is virtually unstoppable and there are no evident weaknesses in his game.
Going into the US Open, which players outside of the top five have the biggest chance of beating the Serb?
Form in 2011: In the Australian Open, Monfils reached the round of 32, as he fell at the hands of Stanislas Wawrinka in straight sets.
He performed excellently at Roland Garros, making the quarterfinals, until he was knocked out by Roger Federer, who would make the finals in a few days.
At the All-England Club, the Frenchman made the round of 32, as he was upset by Lukasz Kabot of Poland in four tough sets.
So far this year, Monfils has yet to win a title, though he did reach the final of the Legg Mason in Washington DC. In that match, he was ousted by Radek Stepanek.
Why He Has a Shot: Monfils came extremely close to beating Djokovic in the quarterfinals of the Western and Southern Financial Open, as he took the Serb to three sets. He was playing some of his best tennis, since he had to raise his game to match the powers of Djokovic.
His great serve, excellent groundstrokes, good footwork and tremendous speed will help him in his efforts if he comes across Nole.
Form in 2011: Berdych made the quarterfinals of this year's Australian Open, and though he lost to soon-to-be champion Novak Djokovic, he did perform well over the course of the tournament.
The French Open was a complete disappointment for Berdych, as he lost in a first-round five-setter against Frenchman Stephane Robert. After that, he was extremely frustrated, and it was impressive that he did not put his head down.
At Wimbledon, Berdych lost in straight sets to American sensation Mardy Fish in the quarterfinals.
He hasn't won any tournaments or gotten into any finals this year, which is not good by the high standards of the Czech.
Why He Has a Shot: In the Western and Southern Financial Open, he got to the semifinals, where he did face Djokovic himself. Despite the fact that he got injured, it's possible he can pick his game up in time for the Open.
Berdych was pounding the ball on every shot, and if he's healthy, he will be a menace in a future match against Novak.
Form in 2011: The Australian Open was a major disappointment for Mardy Fish, as he lost in the round of 64 to Tommy Robredo of Spain.
The French Open wasn't too great for him, either, since the American lost in the third round to Frenchman Gilles Simon.
He did well at Wimbledon, where he lost to top seed Rafael Nadal in the quarterfinals at the All-England Club. Despite that, he managed to take a set off of the Spanish Bull, and he probably wasn't too confident of winning that match.
It was in May that Fish finally managed to break into the top ten, after being on the verge of doing so for a while.
Why He Has a Shot: Fish is playing the tennis of his life right now. His shots are harder and more consistent than they ever have been, and he even managed to beat Rafael Nadal.
NOTE: He would be higher on the list, but he picked up a recent injury. Despite that, he should still stand a chance against Djokovic, whom he did come close to beating earlier this month.
Form in 2011: For someone as talented as Juan Martin del Potro, losing in the second round of the Australian Open is not very good; he was toppled by Marcos Baghdatis in four sets.
At Roland Garros, Delpo lost in the round of 32, but only because he came across Novak Djokovic, who was then undefeated on the year. (He did take a set off the Serb, though.)
At Wimbledon, he could have gotten farther if he hadn't met Rafael Nadal in the round of 16. He played well, taking a set off of the Spanish Bull, but Rafa proved too much for him to handle.
Apart from grand slams, Del Potro has won two tournaments this year: Estoril (a clay tournament in Portugal) and Delray Beach (hard court tournament in the USA).
Why He Has a Shot: Del Potro is currently one of the hardest hitters in the game. His forehand is loaded with tremendous power, and is very flat, as is his backhand. At 6'6", he is a big server, as his serves come down from a very tough angle to return.
The Argentine is one of the biggest hitters in the game, and he is capable of hitting through Djokovic, which might pay off in a meeting of the two.
Form in 2011: Tsonga had a mediocre performance in the Australian Open, as he got to the round of 32. However, he was defeated by Ukrainian Alexandr Dolgopolov—who played the tennis of his life—in five sets.
He got to the round of 32 at Roland Garros, also, where he was ousted by Stanislas Wawrinka in five.
Tsonga's Wimbledon run, however, was sensational. En route to the semifinals, he beat Fernando Gonzalez, David Ferrer and Roger Federer. Though he lost to Djokovic, it was an excellent performance overall.
He hasn't won any tournaments so far this year, but he got to the final of Queen's Club and Rotterdam.
Why He Has a Shot: Like Del Potro, Tsonga crushes the ball on every shot. He has consistent groundstrokes, a huge serve, and excellent touch at the net.
This helped the Frenchman take a set off of Djokovic at Wimbledon, and maybe next meeting, he can win more than just one set.
Roger Federer, Rafael Nadal, Andy Murray and David Ferrer could not be included on this list, as they are all currently in the top five.
Nadal seems tactically at a loss against Djokovic, since he has tried several methods of beating the Serb, though none of them have worked. At one point, Djokovic was so great that Nadal had to resort to moonballing, a strategy that is looked down upon.
No one is really sure whether Federer can beat Novak again, though he did it once in June. He did play sensationally, so he would have to emulate that performance in order to beat Novak. The chances of that happening are low, but you can't rule out the Swiss Maestro.
Murray was the other player who beat Nole; it was in the final of the Western and Southern Financial Open. The Great Scot was exquisite, and he really deserved the win, despite the fact that Djokovic had to retire.
Is it possible that Djokovic is too hurt to play at Flushing Meadows? Will his game become weaker as a result of injury?
Well, we'll just have to see.