The ATP is arguably in the midst of some of its best years of all time, with a leading selection of elite stars dominating the slams and taking tennis to the next level. In recent times the slams have been all about the battles between Rafael Nadal, Novak Djokovic, Andy Murray and Roger Federer, who have been dubbed the 'big four' by fans and pundits alike.
Whilst these players have held a stranglehold on the majors there's only so long that this can continue for. Firstly, Federer is now 32-years-old and the cracks are showing as he's slipping away from the top of the rankings.
Nadal's situation is also debatable. The Spaniard has been nothing short of sensational in 2013 but it remains to be seen how long he can maintain his current level. He's overcome his knee injury for now. The question is, 'will he be able to stay injury free and remain a leading light into his thirties?' He's still only 27, so it's hard to know what to expect. There could be a lot of magic left in the Mallorcan. Nadal and Djokovic were dominant in 2013. (Photo by HECTOR RETAMAL/AFP/Getty Images)
That leaves Djokovic and Murray, who are both 26 and were born a week apart. Both play a brutally physical game that will be hard to sustain as they enter the twilight years of their careers. Regardless, both men could very realistically still have five years left at the top of the game. Murray is just making his return from back surgery and seems to be making steady progress. It's likely that he'll be capable of big things in 2014.
The most notable threat to the current order is Juan Martin Del Potro. The Argentine is a slam winner himself and appears undaunted by the ATP's stars. Importantly, he also has the firepower to dictate terms against these players, and that quality is severely lacking in the rest of the top twenty. Should Delpo make a real breakthrough in 2014 it's likely that he'll simply replace Federer as the fourth member of the big four, or we may even briefly enjoy a 'big five' if Federer can find a way to roll back the years.Andy Murray will make his eagerly anticipated return in 2014. (Photo by Shaun Botterill/Getty Images for HEAD)
Looking further down the ATP rankings it's hard to find an immediate threat to the big four. There are a lot of players with huge potential but it might be a while before any of them get their hands on the biggest trophies. This isn't to say that there's a lack of willing challengers. Bernard Tomic, for instance, recently stated, "generations will move on, for sure in two or three years there will be no Federers." He added that he hopes to be one of the stars of the next generation. The recent pictures of Tomic enjoying a lap dance and partying on the Gold Coast might encourage people to take him less seriously, though he insists he'll be training hard from next week onwards.
There are a few other up-and-comers to look out for, including Grigor Dimitrov, Jerzy Janowicz and Milos Raonic. Dimitrov has won a lot of fans for his graceful style of tennis and superb shotmaking, yet consistency has been lacking. As for Janowicz, his size, serve and forehand make him a force to be reckoned with. His movement isn't too bad either and he outlined his slam credentials by reaching the Wimbledon semi-finals. As for Raonic, his serve is one of the most lethal weapons in the game. He's making impressive progress under the guidance of Ivan Ljubicic too, who seems to be moulding him into a more rounded player.Tomic is a huge talent, but he can't expect slam titles to fall into his lap...(Photo by MIGUEL MEDINA/AFP/Getty Images)
So will there be an upheaval at the top of the rankings? For now it seems unlikely, and if Djokovic, Murray and Nadal can stay fit, all three could be set to dominate for the next three years, maybe more. It would be wishful thinking to expect to see Federer in the frame at that stage, though Del Potro is shaping up to be a worthy replacement.
If we're to see significant changes in the next few years it will be up to the young guns to step up and improve. There are a lot of extremely talented players coming through, yet the standard required to compete with the current slam contenders is remarkably high. Whether or not anybody proves to be capable remains to be seen, and with the ATP's stars showing their current amount of professionalism and dedication, it will take a tremendous effort to shake things up.