Former tennis pro Marc Rosset has given an insight into Roger Federer's mindset during the time when there were doubts about him getting back to his best and challenging for major honours.

The Swiss ace failed to win a Grand Slam title for over four years since his triumph at the 2012 Wimbledon Championships, during which time Novak Djokovic was the dominant force in men's tennis. Federer and Djokovic played 12 finals between 2012 August and 2015 November, of which the Serb won nine.

A number of questions were raised and there were suggestions that Federer was past his best, with many calling for him to hang up his racket. The Swiss tennis legend however remained unfazed, according to Rosset, as he continued to persevere and find a way back to the top.

In 2016, Federer was struck down by injury, which forced him to miss the final six months of the campaign. The 36-year-old took time off on the sidelines to recover and work on his game before returning at the start of the 2017 campaign. And he has been on a roll since.

Federer has silenced all his doubters – he has won nine titles in the last 13 months, which includes three Grand Slams titles, taking his tally to 20. Apart from his titles, the Swiss maestro has returned to the top of the world rankings, becoming the oldest world number one in men's tennis since the rankings were introduced in 1973.

Rossett admits that Federer, despite all the fame and adulation he has received over the years, remains "absolutely normal" like anyone else. The former Switzerland David Cup captain also suggested that Federer resurgence does not surprise him since he never doubted his compatriot's ability to add more major titles to his kitty.

"I see it as an absolute prize for his tenacity," Rosset told L'Equipe, as quoted by Tennis World USA.

"When he lost to [Novak] Djokovic, he wasn't that far and people said that he wouldn't win anymore and that it was the end. The guy kept trying to find solutions and this shows he was right.

"I asked him the same question after Lille [2014 Davis Cup final] on the airplane, he said, 'They wrote so many beautiful things on me that it doesn't matter if it's a little bit worse now'," the former world number nine explained.

"He is always living the moment, except when he is making his schedule. He is not different. He is absolutely normal. In his behaviour, he is almost Mr Everybody."

"He doesn't surprise me. I always said that he would win a Grand Slam. So I don't say, 'Wow'," Rosset added.

Roger Federer
Roger Federer was crowned the oldest world number one when the rankings were revised on Monday, 19 February Getty