Murray is on song but still in shadow of Djokovic, says McEnroe
Andy Murray is in the form of his life but still a long way short of Novak Djokovic at his best, according to seven-time grand slam champion John McEnroe.
Murray begins his US Open campaign on Tuesday against world number 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 of 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. I don't think Murray would go in as a favourite on that surface against Nadal in a best of five."
Murray cannot meet either Djokovic or Nadal until the final in New York but should he get there, the Scot will become only the fourth man in the Open era to make all four grand slam finals in a calendar year, joining Federer, Djokovic and Rod Laver.
He has also reached seven consecutive finals heading into the last major of 2016 and with coach Ivan Lendl back by his side, the 29-year-old looks primed for another challenge.
"Murray is playing the best tennis of his life. He seems to have everything in order. He's in a good space," McEnroe said.
"He wants to get closer to be talked about in the same breath as these three guys that are like three of the five greatest players that ever lived.
"So Murray has been meticulous. He's done a great job. But he's still got a ways to go to even get close to those guys."
Meanwhile, McEnroe has ended his coaching partnership with Canada's Milos Raonic.
McEnroe joined Raonic's team as a coaching consultant for this summer's grass-court season but came under scrutiny when continuing to commentate on his player's matches at Wimbledon.
Raonic, whose primary coaches are Carlos Moya and Riccardo Piatti, reached his first grand slam final at SW19 with the American by his side, before losing to Andy Murray.
But McEnroe's media commitments mean he and Raonic have decided to part ways.
"It ended up becoming an issue at Wimbledon," McEnroe said.
"He's got a great team around him. I think it's best and easiest at this point. This week I was with him, but having thought about it, and for Milos' sake, for ESPN and my sake, I think it's best that we stop right now doing what we're doing."
"So when the US Open starts on Monday, he's got his people. I'm pulling for him and want him to do well."
McEnroe was unsure whether the partnership might resume after the US Open.