Novak Djokovic on Wednesday said breaking Roger Federer's record of 17 Grand Slam titles was one of his main motivations as he looks to prolong his stay at the top of men's tennis.

The world No 1 said Federer's magic total wasn't out of the question after a year in which the Serb contested all four Grand Slam finals and won three of them, taking his total to 10.

"Nothing is impossible. I have that kind of mindset. I know that it's still a long way to break his record," Djokovic, 28, said at the Shanghai Rolex Masters, after cruising past Martin Klizan 6-2, 6-1.