Rafael Nadal wants to overtake Andy Murray as world number one and believes Roger Federer poses the biggest threat to him.

The 31-year-old Spaniard and Federer have both enjoyed a renaissance in their tennis careers this year, with Federer moving on to 19 Grand Slam titles following success at both the Australian Open and Wimbledon, while Nadal claimed his 10th French Open crown.

Both men are lining up behind Murray and one is poised to take over as the world's top-ranked player by the end of 2017.

Murray, who has had a frustrating season due to injury and a loss of form, must defend 5,460 points in the second half of the year while Nadal has to defend 390 points.

Federer has nothing to defend given that he has won five tournaments - more than any other player in the men's game.

Nadal is certain it will be a straight fight between the old rivals to be the number one at the end of this calendar year.

He said: "It's true that we [Roger and I] are better prepared to compete for nice things at the end of the year, but it depends on what we’re able to do from now until the end of the year. We’ll have to wait and see.

"The person who will be able to keep his high level for a longer period of time will have more options to fight for the world number one ranking.

"But the same can be said of Murray and many others who are up there. Maybe they haven’t had the best six months this year, but they are also candidates."