Novak Djokovic has claimed that the likes of Andy Murray, Rafael Nadal and Roger Federer fuel his desire to remain the number one ranked tennis player in the world.

The 28-year-old has already won the Australian Open and Wimbledon this year and is the favourite to pick up the top prize at the US Open this month.

The Serbian is currently number one in the world ahead of second-placed Federer and third-placed Murray, but Nadal's lack of form has seen him drop to eighth.

"Obviously each season one of the goals is to try to get to number one of the world. To get to number one of the world, you need to be consistent throughout the entire year. Tennis nowadays, men's tennis, is so competitive," Djokovic told reporters.

"With the guys like Murray, Nadal, Federer, they are going to do everything in their power to be consistent and to get the number one. That's what motivates me even more. So we push each other."

Djokovic will meet Roberto Bautista Agut in the fourth round of the US Open.