Having contested matches against some of the greatest players to ever step on a tennis court, John McEnroe has some valuable insight into tennis’ current generation of stars.

McEnroe, a seven-time Grand Slam champion himself, was one of the four legends present at Novak Djokovic’s on-court ceremony on Friday afternoon in London, where he was crowned the year-end No. 1 for the third time in four years.

Only seven other players have ever achieved that feat, one of whom is McEnroe.

“That shows me that he has become one of the greats of all time. He is going to be there a couple more years. He looks so rock solid, it’s incredible,” said McEnroe.

The infamous Wimbledon champion even suggested that Djokovic could win his elusive French Open title and complete the Career Grand Slam in 2015.

“If Rafa is not healthy, that might open the door for him to win the French Open (the one grand slam to elude Djokovic). I would say the greatest players that ever lived are Roger (Federer), Rafa (Nadal), my idol Rod Laver and Pete Sampras.”

While McEnroe would not consider Djokovic above Federer and Nadal just yet, he has no doubt that he is in the Top 10 list of the greatest male tennis players – and rapidly rising through the ranks.

“I wouldn’t put him there yet but in the top 10 and maybe he is moving higher as each minute goes (by). The good news (is that) he is getting better and by the time I was his age I was getting worse!”