The ever outspoken and eccentric former star whipped out an acoustic guitar to "reveal in a nutshell my belief that there should be no warm-up in tennis".
McEnroe, who now works as a TV pundit and analyst, made the "suggestion - one that may not be popular at all" as part of his role as 'Commissioner of Tennis' for Eurosport during the French Open.
"Come on, we're just tennis players - we're not laying our lives on the line," he sang.
Caroline Wozniacki pulls out of Roland Garros
"Don't we want to make the sport more exciting?" he questioned.
"We've got to start thinking outside of the box!"
Does McEnroe have a point when he says that pre-match warm-ups are a waste of time in professional tennis? After all, players do often come straight from the practice courts themselves for their matches. Post your views below...