John McEnroe says his comments regarding Serena Williams were fair comment after suggesting she would be ranked 700 in the world in the men's game.

Seven-times Grand Slam winner McEnroe claimed the women's 23-times Grand Slam champion Williams was "the best female player ever" but declined to label her the best overall.

"If she played the men's circuit she'd be like 700 in the world," he said.

"That doesn't mean I don't think Serena is an incredible player. I do. And on a given day, Serena could beat some players... But if she had to just play the circuit -- the men's circuit -- that would be an entirely different story."

Speaking to CBS, Eurosport pundit McEnroe later expanded on his stance on the matter and added that he would like men and women to play each other to settle the debate.

"I felt the need, however unfortunately, to defend myself and say what I really felt, which is about what I think she would be," he said.

 Quizzed on whether he would like to apologise to Williams, McEnroe said:

"No. I didn't know it would create controversy. I've said this 1,000 times.

"I don't want anything to go wrong with Serena because she's pregnant, I don't want to upset her. I think she's doing it tongue in cheek as well and I think deep down we're talking about something..I can't even believe we're talking about it."

The world number 701 Dmitry Tursunov, a 34-year-old from Russia who was once ranked as high as 20 in the world, has supported McEnroe's claims by adding that he believes he would beat Williams.

Outrage towards McEnroe for his Serena remark is absurd. Read the transcript. He was asked directly for a comparison pic.twitter.com/W9L97cXsXj

— Oliver Brown (@oliverbrown_tel) June 27, 2017

Plus, Serena herself told Letterman in 2013: 'If I were to play Andy Murray, I would lose 6-0, 6-0 in five to six minutes' pic.twitter.com/1RLRmnQb1M

— Oliver Brown (@oliverbrown_tel) June 27, 2017

"I would hope that I would win against Serena," said Tursunov in an interview with the BBC. "It would be a similar argument to: who would run faster, the fastest woman or the fastest man? Tennis is becoming more and more a physical sport, so it's going to be hard for a woman to beat the men.

"It's not black and white. There are lots of factors to take into account. Physically I might not be in the best shape of my life, but as an overall package, I'm much better than my ranking would suggest. She is pregnant, and I'm not.

Former world number one Williams, who won the Australian Open in January while pregnant and since has taken time off to have her baby, responded on Twitter, saying:

Dear John, I adore and respect you but please please keep me out of your statements that are not factually based.

— Serena Williams (@serenawilliams) June 26, 2017

I've never played anyone ranked "there" nor do I have time. Respect me and my privacy as I'm trying to have a baby. Good day sir

— Serena Williams (@serenawilliams) June 26, 2017