The three players have spent much of the past two decades battling to be seen as the greatest male tennis star in history and Federer thinks that Djokovic didn't reach the same levels of popularity because he emerged later on.

Speaking in the Amazon Prime documentary 'Federer: Twelve Final Days', the Swiss great said: "I guess he was the party crasher of Rafa and Roger fans.

"There was a lot of Rafa-Roger love there, so when Novak came probably a lot of people said, 'Look, we don't need a third guy. We're happy with Roger and Rafa.'"

The 20-time Grand Slam winner added: "The Federer fans at the beginning didn't really like him because they just thought, 'Roger's a bit more easy, he does it with ease.'

"Then Novak came in with his strong personality and that unbelievable grit of wanting to win at all costs. I think also Novak was triggered by the relationship with the fans. I think that deep focus maybe scared some people away.

"I think he's been a little bit misunderstood. I look past the media and I see at the end the man he is. If I take away his game, who is he? What are his values? I know he cares very deeply about his family."

Federer admits that he was "unconvinced" about Djokovic when the Serb first broke through but has huge admiration for what he has gone to achieve in the sport.

The retired ace said: "I played him in Monaco the very first time (in 2006) and I walked off the court and thought, 'Yeah, he's OK'.

"Even though there was some hype around him, I wasn't really fully convinced. I think I didn't give Novak the respect he deserved because of his technical flaws.

"I felt like Novak had a very extreme forehand grip and his backhand for me wasn't as fluid as it is nowadays.

"But then he ironed those things out super well and became an unbelievable monster of a player."