At 27 years old at the peak of his game, Novak Djokovic really has very few contenders for the No. 1 position. Looking at Roger Federer firstly, 2015 will surely be his only chance of sneaking to the top of the rankings. Points to defend over the clay court season include a final at Monte Carlo, a R32 at Rome, nothing in Madrid, and only a R16 at the all-important Roland Garros. However, at over 4000 points behind Djokovic, he really needs to extend his current form and hope for a drop in Djokovic’s game. In their general head-to-head, Federer could best hope for a 50-50 split in their results over the next year, which in the rankings points, may only lead to a small gain.

Next we look at Rafael Nadal, who this writers believes is the only one who can dethrone Djokovic at peak form. The problem for Nadal though, is injury. In current form, it’ll be surprising if he finishes the year inside the top four. With his physical presence no longer there, he really can’t impose his game on his opponents like he has for his entire career. Recent losses to Verdasco and Raonic show just how out of touch he is. Both opponents would normally be easy beats for Nadal, but without his powerful defensive game, these types of players can dictate terms and give Nadal no easy balls. If he can get back to full form he certainly gives Djokovic some form, but this writer would be really surprised if he wins any more Grand Slams aside from Roland Garros.

It’s hard to see Federer and Nadal continuing past 2016, and with Andy Murray seemingly destined to be the No. 2 of Djokovic’s age, who of the up and comers can threaten Djokovic for the No. 1 position? For overall consistency on all surfaces, this writer sees Grigor Dimitrov developing into a real threat. At the moment, he still lacks experience and calmness in the big moments, costing him many matches in big tournaments so far throughout his career. Only matches and years on the tour will solidify this, so this writer expects him to become a force midway through 2016.

Kei Nishikori also looms as a threat for the rest of Djokovic’s career. With a breakout 2014 in the books now, Nishikori’s biggest task now is to break out of the mould that David Ferrer has carved for the counterpuncher high in the rankings. Does he have the consistency to be a threat throughout the year? The only other name to watch over the rest of Djokovic’s career is Milos Raonic. As far as challenging him for No. 1, this writer is afraid his one-dimensional game will really limit him to success on the faster courts, even if that one dimension is probably the best in the game.

Now to the man himself – how long can he keep this up? He is in the physical prime of his career and rarely comes down with an injury despite his monstrous defensive game and aggressive sliding on the hard courts. In his physical prime, there is no way any player can consistently dominate Djokovic and take the number one ranking from him. This is clearly shown by his gap over the field which currently sits at over 4000 points to Roger Federer, and nearly 8000 to outside the top four.

So where does that leave Djokovic for the rest of his career? This writer is tipping he’ll go very close to Federer’s record, even if he needs a little over three more years at No. 1 to take the record. Assuming he stays injury free, this writer thinks he’ll have at least another two years in top physical condition – a condition where he is relatively untouchable. That takes him to the age of 29, and with only 56 weeks left to topple Federer.

Regardless of the current and up-and-coming talent, Djokovic will remain at the top of the rankings for quite some time yet. Much of his remaining years will be spent dedicated to maintaining peak physical form giving him the best possible chance of breaking records along the way. With Federer and Nadal gradually losing time and the ability to topple the Serb, there is every chance Djokovic will end his career as the new record holder for weeks at No. 1.