Murray begins his US Open campaign tomorrow against world No 82 Lukas Rosol and he arguably starts as tournament favourite after winning both Wimbledon and an Olympic gold medal this summer.
A fourth grand slam title at Flushing Meadows would also represent a significant power shift given only two months ago Djokovic held all four major titles.
With Roger Federer out injured, Djokovic wrestling with “private issues” and a niggling wrist problem, and Nadal searching for his first grand slam semi-final since the French Open in 2014, there appears finally to be an opening for Murray’s own period of dominance.
But McEnroe, who toiled with the likes of Bjorn Borg, Jimmy Connors and Ivan Lendl, believes it is still too soon to dismiss Murray’s biggest rivals.
“Can Murray dominate now? I think Novak is still obviously the most obvious obstacle,” said McEnroe.
“He’s been playing at a level the last couple years that Murray hasn’t been able to attain. That’s frustrated him.
“Things have changed the last couple months, the shock that he lost early at Wimbledon, but to me the level that Novak was playing, it was higher consistently. The bar was higher maybe than anything I’ve ever seen as far as his consistency.
“There’s a way to go where he would be able to lift it to do what Novak has done the last couple of years and is going to continue to try to do.
“And Nadal on clay, at a French Open, you’re not going to convince me he’s done yet the way he was playing leading up (before withdrawing injured) – I thought he was getting close to what he was before on the clay.
“That would be an interesting match, to say the least, with Murray.”
Beverley’s Kyle Edmund has a tough first-round match-up today with experienced Frenchman Richard Gasquet.