The ATP schedule is, without a doubt, incredibly demanding and allows for little to no mistakes to be made.
Rafael Nadal, Novak Djokovic, Andy Murray and David Ferrer are among the top grinders in the game and are constantly running marathons and rapidly switching directions in lengthy, dramatic matches.
Roger Federer, similarly, plays a great deal of matches simply because he wins consistently, though he has never had a truly significant injury.
Nevertheless, some tournaments over the course of the calendar year ask for a lot from the competing players and in several cases the events take their toll on the top athletes.
Here are the most difficult, taxing tournaments in the world in order.
Of the ATP1000 events that take place on hard courts (excluding the World Tour Finals for now) this one comes in second place.
Not only does it take place in blistering heat (in the middle of the California desert) but the game-play is always very physical.
The matches also get especially difficult at the semifinals stage—more so than most other tournaments. Even at this past event, Federer beat Nadal in a masterful performance while John Isner took out Novak Djokovic in a third-set tiebreak.
The final between the Swiss and American was perhaps decided by one point in the first set tiebreak that Federer would win.
The most physical match of this tournament had to be Nadal v. Nalbandian, wherein the Spaniard struggled to win extended baseline rallies.
Madrid has always proven to be a grueling tournament, even given red clay standards.
Rafael Nadal, Novak Djokovic and Roger Federer have been the three athletes that have performed consistently in recent years at this event, though the temporary blue clay switch was especially difficult for players.
Of the ATP1000 clay events, this one requires the most effort and inspiration.
Plus the top players are more often seen playing in this tournament than Rome and Monte Carlo.
One match that could sum up the fact that this event pushes people to the limit is the Djokovic-Nadal semifinal in 2010, which, at the time, was an unusually lengthy three-setter.
The ATP1000 competition that most closely resembles the Australian Open is the Shanghai Rolex Masters.
Though it has only been around for a few years this tournament has put forth classic match after classic match.
The courts play slow and the match-ups always turn out to be fantastic fits.
My personal favorite match at this tournament was Djokovic-Davydenko in 2009.
Obviously this tournament was going to go in this slot. It may be an even tougher event than the US Open, but the wind and constant rain in Flushing Meadows allowed it to stay in a more grueling category.
You play a Top-8 player, get a day of rest, and repeat the process twice.
All of that only gets you to the semifinals if you win twice and have a better record than two of the other players in your group.
The one good thing about the round robin format is that you can both defeat and lose to somebody in the same tournament, but other than that, this tournament requires 100 percent efficiency and constant capitalizing on opportunities.
Again, the rain and wind that come over Flushing Meadows makes this Major very difficult, though it is probably the easiest to win in terms of what you must do over the two weeks.
The courts are incredibly fast—perhaps even more than Wimbledon now, though the bounce remains much different.
Up until 2009, athletes were unable to dethrone Roger Federer in New York (which was similar to his position in Wimbledon). It took a tremendous effort to finally break through and steal the title, which further reinforced just how difficult it was to win the tournament in the modern era.
Today, the man to beat in this tournament is Novak Djokovic. He has been the second-most consistent performer, reaching several finals and winning the title last year.
The schedule is difficult, as is every major, though the court one plays on in the setting does play a large factor in who moves on to the next round.
Of course, rain is also very domineering in England but the new retractable roof allows for a different environment.
The very quick, slippery surface with low and awkward bounces makes it tough to develop a rhythm. If you don't play quick, power tennis then you may not stand a chance anymore.
Players with weak serves are especially penalized in this Major, though the power players can do fairly well nowadays.
This is my favorite tournament (as I've said many times before) in the world but there still is one tournament that beats it in the "difficulty" category.
Not only is the court surface perfect for good baseline points but the actual matches are always thrilling to watch.
Unfortunately for the players, each match always takes place either in the burning sun or lasts until the late hours of the night.
It seems that more five-setters occur here than in other tournaments, and there are so many extended fifth sets. Also, more upsets occur here because of the tough matches and the difficulty that comes with closing them out.
Alas, we have Roland Garros. If you can beat Rafael Nadal in this event, you still aren't guaranteed to win it (ahem, Robin Soderling).
And even if you beat Roger Federer, it seems that that gets you nowhere (ahem, Robin Soderling and Novak Djokovic).
For Rafael Nadal, it may seem that his path to the championship is always easy but it is far from that. He exerts so much force day in and day out, and his bodily injuries show that the sliding and excessive effort takes a toll.
Who knows if he will be healthy enough to win it again this year? Regardless, it will take a courageous warrior to break through the two-week barrier.
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