The two have become the most successful players in history with Federer winning 19 Grand Slams and Nadal 16.

They have endured some thrilling battles against each other and are one of the biggest rivalries in sporting history.

And being five years older Federer remembers what Nadal was like when he first started playing at the top.

"At the beginning, he was very shy and respectful with other top 10 players, and especially because I was No. 1," Federer recently told Tennis World.

"Then as the time went on his personality increased and he started playing his chances.

"It was interesting to see him growing up until that he became the champion he is today.

"We had hard and painful battles on the court, issues as well, but there was always an enormous respect between us.”

And Federer admits without Nadal’s presence he wouldn’t have been the player he has been.

Both men dropped off over the last few years with Novak Djokovic and Andy Murray dominating but have returned to the top of the sport.

Nadal is back at world no.1 with Federer second in the rankings.

They have won two Grand Slam titles each this season with Federer’s win in Australia his first slam since 2012.

While Nadal’s Roland Garros win was his first since 2014.

"He will forever be my ultimate opponent,” Federer said of Nadal.

“He was the one who helped me to improve the most and to be a better player.

"And at the same time I say if he didn't exist, I would have not won so much (laughter). Rafa's presence was an extra motivation."