The Serb has set up a blockbuster semi-final against world number one Jannik Sinner at Roland Garros on Friday (06.06.25) but the tennis legend says that the odds are stacked against Djokovic in his bid for glory in Paris.
McEnroe told TNT Sports: "I've been lucky to have this job for 30 years and 20 of it watching this legend do his thing time and time again.
"It doesn't surprise me in a way - it amazes me - but it doesn't surprise me that he's still able to play at this level, that he wants it still this badly. It's rather remarkable."
The seven-time major winner says it "would make sense" for Djokovic to win a historic 25th Grand Slam title at the French Open but knows that it will take an almighty effort for the great to beat Sinner and then triumph in a potential final against Carlos Alcaraz.
McEnroe said: "As time goes on, even he, you would think it would get tougher for, but this is going to get a whole lot tougher
"I’ve got news for you. Sinner’s come to play, he's playing incredible tennis. Alcaraz was electric as well and I expect him to beat (Lorenzo) Musetti so he’s going to have to rise to the occasion even more and play even better to win this tournament."
McEnroe believes that Djokovic's best chance of beating Sinner is by turning the match into a gruelling battle.
The former tennis star said: "The path tactically is to do what most guys need to do is just serve big. He's going to have to use the crowd, which I think will be behind him. He'll be the underdog coming into the match, and he's going to have to – believe it or not at 38 – test Sinner, who hasn’t played that much tennis, hasn’t lost a set.
"The longer it goes, there could be a question of where his fitness is at and if the nerves get to him. So that’s what he’s going to try to do."