Roger Federer has revealed that he was surprised to see long-time rival Rafael Nadal as the top-ranked men's singles player in 2017 but admitted that he had no doubt the Spaniard could return to winning ways after struggling with injuries in the past couple of seasons.

Nadal and Federer occupy the top two spots in the rankings at the moment after both players picked up five titles apiece which includes sharing the four Grand Slams between them. Both of them have surprised many this season with their return to form especially since they were ranked No 9 and No 16, respectively at the start of the year.

The 36-year-old Swiss ace's surprise is based on events from the past year, when both of them struggled to play an exhibition match during the opening of the Rafael Nadal Tennis Academy in Mallorca, as questions about their future in the game were raised.

Moreover, Andy Murray and Novak Djokovic, the top two players from last season were expected to continue their domination this season. But the duo has struggled for form and fitness this year giving Nadal and Federer an opportunity to make their way up the leaderboard, something the Swiss admits he did not foresee.

The top two ranked players are now set to battle it out in the final part of this season for the prestigious year-end number one ranking. Nadal currently holds the advantage with a 1960-point lead over Federer, but good results in the upcoming events can see the 19-time men's singles Grand Slam winner overtake his long-time rival. However, he has admitted that remaining fit until the end of the campaign will take priority over chasing the number one ranking.

"Am I surprised that he's world No. 1 right now? Maybe a little bit, just because last year we were at the academy both injured, not knowing where our careers were going to go," Federer said, as quoted by the Metro.

"I'm not surprised he came back and won the French Open and he wins Grand Slams again and that he was in contention for world No.1.

"But then being world No. 1 is a whole different story. For that you also have to see how Murray was going to play, and Djokovic was going to have a word to say, obviously. We didn't know they were going to get hurt and not have their best season," he added.

Roger Federer
Roger Federer and Rafael Nadal played doubles together for the first time in their careers Getty