John McEnroe was 43, a father of six, doyen of commentary boxes on both sides of the Atlantic, Superbrat had become the grey-haired sage, when he decided to publish his autobiography. It raced to No1 on the New York Times bestseller list.

It takes a lot to shock the game's greatest Shockmeister, but a book at 21? “Isn't Andy Murray a little young for that?” McEnroe said yesterday. “Hopefully there's another one to be written but I would have thought of it as bad luck to have written a book so young. If it's viewed as it should be, it's about a guy at the beginning of his career.”

McEnroe is thinking Wimbledon, which starts on Monday, where he will be spending his ninth year as the voice that has to be heard on the BBC's coverage. He is going to miss Jimmy Connors as a sparring partner this year, but Tim Henman is moving in, fire and ice personified. One suspects they will be the team for the first Murray match. Can the Scot put in his dodgy thumb and pull out a plum?

The 49-year-old New Yorker says he does not know Murray at all, but arm's length is close enough to gain a vivid impression. “From what I saw in Paris, I thought the [coaching] entourage was interesting - interesting for a while,” he said. “[Brad] Gilbert [his former coach] was talking quite a bit I presume. With [Alex] Corretja [who worked with Murray in the clay-court season], from what I hear there wasn't a whole lot of chance to buckle down and really be a coach. It reminded me a bit of when I was asked to do it with [Boris] Becker and it was obvious he was doing exactly what he was going to do anyway, I changed absolutely nothing. He wanted me around but when push came to shove, he didn't want to change anything.

“Murray has something about him. It depends how you let out emotion. Most of my career I could do it and something good would come from it. There's a line where it starts to become the law of diminishing returns, you've got to know yourself ultimately. I think it could help him at the right moments. I've also seen it where it has hurt him. Instead of digging in, he has slipped and I've seen that with lots of people. I feel it's definitely time for him to step up a bit, he has good hands and comes to the net sometimes. This is a great opportunity for him to move up.”

The final of the Artois Championships on Sunday, though, was a revelation of how far Murray has fallen behind the world's second and third-best players, Rafael Nadal, the champion at Queen's Club, and Novak Djokovic, of Serbia. McEnroe was transfixed. “What Nadal has done is pretty amazing,” he said. “His serve was a bit of an issue and he wasn't coming to the net much but that has changed. Nadal moves on grass like he does on clay, which is how Björn [Borg] made the transition. Nadal beats himself up on hard courts but not on grass.

“It's great that Djokovic is right there in the mix. He walks around with that strut and he's sticking that chest out like Boris did when he was younger. I'd be surprised if he doesn't win a few more majors. But the pace they are hitting the ball is insane, I hit the ball harder now than I used to when I was a champion. It's the strings. They are going to pay a price. We pretend there's not a problem.

“We are comparing Murray with guys [Nadal and Djokovic] who could be No1 in the world. I would like to see how hard Djokovic works compared to Murray - that would be my first question. Djokovic has incredibly good flexibility because of his core area; he has got this incredible variety of serve. Andy seems stronger and fitter and has got over the cramping problems and made headway but there's more progress needed obviously. His serve has picked up. The easy solution is to get in even better shape. It's unbelievable how good a shape they [Nadal and Djokovic] are in.”