Novak Djokovic of Serbia plays a backhand against Matteo Berrettini of Italy in the final of the men’s singles final during the Wimbledon Championships on July 11. Photo: VCG

"Novak, you're the GOAT!" shouted those Novak Djokovic fans that had been lucky enough to get tickets to see the Serbian superstar play in the men's singles final at Wimbledon on July 11.

Djokovic saw off the challenge of Italy's first ever men's singles finalist Matteo Berrettini to win his 20th Grand Slam title - moving level with his longtime rivals Roger Federer and Rafael Nadal.

The debate as to who is the Greatest of All Time (GOAT) can only rage on.

"It is incredible because in all other sports you have debates. Lionel Messi or Maradona? Michael Jordan or LeBron James?" former Wimbledon winner John McEnroe told the BBC.

"It's rare when you get three guys who are playing at the same time and it would be hard to argue they aren't the best three players ever... That's not just based on the number of majors, but their overall bodies of work."

Longest record

They may be level on the number of majors though Djokovic has spent more time as world No.1 than both of his rivals - 18 more weeks than Federer and 119 weeks more than Nadal. He also has a winning record against both of them.

McEnroe is among those to back Djokovic to surpass Federer and Nadal for grand slam successes.

"Djokovic is playing better than he has ever played," he told BBC Sport after watching the 34-year-old cruise to another Wimbledon win.

"I think he will probably win at least four or five more, obviously depending on staying healthy. Djokovic has put himself so far out in front of everyone in terms of his ability to embrace what he is doing - in terms of creating history - and being able to execute under a lot of stress.

"You're trying to break the all-time records - there is a lot of pressure. He's able to play his best tennis at this point.

"You expect that to go on for another couple of years, unless someone steps up and realizes how great they are."

Former Wimbledon winner Goran Ivanisevic, who won the 2001 men's singles, is now part of Djokovic's backroom staff. The Croatian thinks that Djokovic could win his next slam as soon as the US Open in September - and in doing so end the GOAT debate once and for all.

"For me, Novak is the best ever. He's writing history. He's going to do it in US Open," said Ivanisevic. "And if he does, I think the story is over. The guy is unbeatable. It's like in the movies, you have to kill the guy 27 times, yet he still gets up.

"I strongly believe he's going to do it. He's going to win all four in one year."

Djokovic thinks he could do it too, as he said at the presentation ceremony on Sunday. "I could envisage that happening. I'm gonna give it a shot," Djokovic said. "I'm in great form and obviously playing well and playing my best tennis at Grand Slams. It is the highest priority that I have right now at this stage of my career."

Golden chance?

What Djokovic might not win is the Golden Slam - all four calendar slams and Olympic gold - which has only been won once before, by Germany's Steffi Graf in 1988. 

The Serb has said that he is 50-50 on going to Tokyo now, as fans are banned and the pandemic has limited the number of staff that can go.

It's not that he is not confident if he does go, as he definitely backs himself in the GOAT debate.

"I consider myself best and I believe that I am the best, otherwise I wouldn't be talking confidently about winning Slams and making history," he said.

"But whether I'm the greatest of all time or not, I leave that debate to other people. I said before that it's very difficult to compare the eras of tennis. We have different racquets, technology, balls, courts.

"It's just completely different conditions that we're playing in, so it's very hard to compare tennis, say, from 50 years ago to today. But I am extremely honored to definitely be part of the conversation."

He certainly has no plans to stop - and he said that his record equaling 20th men's singles Slam victory will only spur on his rivals.

"It means none of us three will stop," Djokovic said when he was handed the trophy for a sixth time.

"I have to pay great tribute to Rafa and Roger. They are legends of our sport and they are the two most important players that I ever faced in my career. They are the reason that I'm where I am today.

"They've helped me realize what I need to do in order to improve and get stronger mentally, physically, tactically. The last 10 years have been an incredible journey. It's not stopping here."

Still, the Serbian was clear that it means as much to win a sixth Wimbledon as his first back in 2011, three years after his first grand slam win at the Australian Open.

"Winning Wimbledon was always a biggest dream of mine when I was a kid... I have to remind myself how special this is, and not take this for granted."