McEnroe on the greatest player of all time

Spain's Rafael Nadal on the practice courts at Wimbledon. Photo / AP

John McEnroe believes that Roger Federer and Rafael Nadal are the greatest ever tennis players.

McEnroe spoke with NewstalkZB's Mike Hosking about tennis, personalities and his new book But Seriously.

"To me Federer and Nadal are the two greatest players that have ever lived. With all due respect to my idol Rod Laver, he's up there too," McEnroe told Hosking.

McEnroe also spoke about the balance between personality and on-court perfection.

"I think it's possible to have both [personality and good performance] I think that if you could harness, say Nick Kyrgios that would be someone who could have it all.

The Big Read: Being John McEnroe

"Because he's go the athletic ability, he's got the game but he hasn't harnessed the mental part of it as yet. And I don't think he can because it's become more athletic, more professional and everyone seems to leave no stone unturned, it doesn't seem to be for the most part as fun, there's a lot more at stake financially and more pressure in a way than ever."

'But Seriously' according to McEnroe is about working at looking at the glass half full.

"The tendency, for me, was to sort of think about 'what if'...instead of getting a better perspective, which I think you have to work at, the point of the chapter and in general what the book is about is, yeah it's easy to say I want to look at the glass half full but you have to work at doing that."