Rafael Nadal
For the fourth time in his career, Nadal will end the year as the world number one in tennis Getty

Rafael Nadal's doctor Angel Ruiz Cotorro has asked the 16-time Grand Slam winner to be realistic and not exert himself beyond limits if he wants to keep fit for a longer stretch of time. Nadal has had a fantastic year thus far, winning two Grand Slams after a long hiatus and was aiming to feature in the ATP Grand Tour finals in London, a tournament he has never won.

The talk comes after Nadal suffered a scare in the Paris Masters as he bid to claim his 31st ATP World Tour Masters 1000 title. He battled to a four-set victory over Uruguay's Pablo Cuevas in the the Round of 16 on Thursday (2 November) and was due to take on Serbian Filip Krajinovic in the quarter-finals on Friday (3 November), but instead called a press conference to confirm that he would not be able to continue in the tournament owing to a knee injury.

More from Rafael Nadal

The win guaranteed Nadal's status as the number one player until the end of 2017, pipping arch rival Roger Federer in the process. The Spaniard is now weighing his options as he considers travelling to London for the tournament that begins on Sunday (12 November). However, Contorro insists that Nadal does not need to push himself and keep himself fit for the Australian Open next year.

"You always have to be optimistic, but also realistic, you have to see that we are at the end of the year, after an extraordinary season," Contorro said, as quoted by the Express.

"Now he suffers some small discomforts within a pathology that we already know, in a tendon in which he has already had ailments in other occasions, and we will try to do everything possible so that he can be in good condition, because he wants to be, is the only tournament he's missing.

"As everyone knows, to be number 1 you have to win many games, and that cluster of matches can be annoying at any moment. If the tendon is holding the loads in a progressive way, you will be in a position to play, if you can not stand it, it is a risk that is not worth running."

Rafael Nadal Roger Federer ATP World Tour Finals