Djokovic thinks he will soon lose top ranking to Nadal
Serb believes Federer's record of 17 slam titles is within Spaniard's reach

Novak Djokovic believes Rafael Nadal may soon displace him as world number one and has plenty of time to break Roger Federer's benchmark 17 major titles after the Spaniard roared to the US Open title.
Nadal claimed the 13th singles slam of his career to move ahead of Australia's Roy Emerson (12) on the all-time list.

Only Pete Sampras (14) and Roger Federer (17) are above the 27-year-old Nadal on the pecking order of major champions.
"Thirteen grand slams for a guy who is 27 years old is incredible," Djokovic said. "I mean, whatever he has achieved so far in his career is something that everybody should respect. No question about it.
"I was saying before, he's definitely one of the best tennis players ever to play the game. Looking at his achievements and his age, at this moment - he still has a lot of years to play."