McEnroe told BBC Sport that the 2015 Wimbledon champion is coming into his prime, and getting stronger.
Djokovic beat Roger Federer on Sunday to make it three Wimbledon titles and nine major wins.
In the Tour de France Team Sky’s Chris Froome believes the pressure is on his rivals.
The British rider leads the tour into the first mountain stage on Tuesday, with American Tejay van Garderen 12 seconds behind.
Froome said: “It’s for the other guys to try to get the jersey from me now.
“This next phase of the race the pressure’s certainly not on my shoulders to be making the race and to be having to try to take time back from anyone.”
Ahead of the second Ashes test, Australian head coach Darren Lehmann has admitted he’s disappointed with Shane Watson’s batting performances.
Watson was out lbw twice in the first test, which England won by 169 runs.
Revealing that there might be changes to the line-up, Lehmann said: “You don’t want to be getting out lbw all the time and you want to make more runs. Shane would be disappointed, so are we.
“We’ll certainly look at the wicket and work out the best XI to win in those conditions and if it means making changes, we’ll make changes,” he added ahead of Thursday’s second test at Lord’s.