Roger Federer has acknowledged he did not give Novak Djokovic “the respect he deserved” when he first emerged as a contender during the great era of men’s tennis.

Djokovic struggled to gain the same levels of support among fans as the likes of Federer and Rafael Nadal because he was seen as a “party crasher”, the 20-times Grand Slam champion says.

“I think he’s been a little bit misunderstood,” he adds of Djokovic in a new behind-the-scenes documentary, Federer: Twelve Final Days, on Amazon Prime.

Djokovic, who has now surpassed Federer’s feats with a total of 24 Grand Slams, was once dismissed as a true great by his Swiss rival, the documentary suggests.

“I played him in Monaco the very first time [Federer won 6-3, 2-6, 6-3 in 2006] and I walked off the court and thought, ‘Yeah, he’s OK’, ” Federer said.

“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.”

For a long time, Federer, Nadal and Andy Murray took more plaudits from fans as men’s tennis reached new levels over the past 15 years.