Rafael Nadal, Roger Federer
Rafael Nadal of Spain and Roger Federer of Switzerland hug at the net, after Nadal won their men's singles semi-final match at the Australian Open 2014 tennis tournament in Melbourne Reuters

World's no. 1 Rafael Nadal is uncertain on his chance of beating the Grand Slam record set by 17-time majors champ Roger Federer, the 27-year-old Nadal said before he plunges into action in an ATP500 event in Rio de Janeiro.

Nadal, who bagged 10 tournament wins last year (including the French and U.S. Open crowns, is surprisingly pessimistic during an interview quoted by Tennis Tonic when asked if he can ever win 17 Grand Slams before he finally closes out his tennis career.

"I don't know if I'm able to reach Federer's record of 17 Grand Slams," said Nadal, who has 13 Grand Slam championships around his belt, trailing Federer by four and American legend Pete Sampras by one trophy.

Throughout the years, Nadal has endured several injuries, including a gruesome knee injury that put his career on hold for 7 months from 2012 to 2013. Recently, Nadal made it to the finals of the Australian Open championship, but failed to bag the gold because of a bothersome back injury.

Nevertheless, Nadal is ready to give his 100 per cent to win every tournament he participates. The Spaniard is set to take on some of the big names in the sport in the 1-week tourney in Brazil before he shifts his focus for the upcoming Masters 1000 event in Indiana Wells, California, and Miami next month.

On the other hand, Federer's strong run in the Aussie Open revived his hope of winning another major crown. Despite his advanced age, Federer has been showing signs that he can still compete at high level, especially with his backproblem no longer an issue.

"Another point is that Federer is still in position to adding more titles to his current total of 17 Majors. The Swiss Maestro was going strong and looking favorite to win the Australian Open but was stopped by Nadal himself. There are bright chances that the Swiss star would be able to solve Rafa riddle at one of the Grand Slams in near future and further stretch his lead over his biggest rival," via Tennis World.

Nadal leads Federer 23-10 in career head-to-head advantage, but the Swiss is still considered the greatest player to ever play the game. Well, at least for now.