John McEnroe has refused to apologise for saying that Serena Williams would lose to the No 700 men’s tennis player.

Speaking to US radio station NPR, seven-time Grand Slam champion McEnroe said of former world No 1 Williams, who has won an Open-era record 23 Grand Slams: ‘If she played the men’s circuit she’d be, like, 700 in the world.’

He qualified the comments by saying: ‘That doesn’t mean I don’t think Serena is an incredible player, and I suppose anything’s possible; maybe at some point a women’s tennis player can be better than anybody.’

But he added: ‘I just haven’t seen that in any other sport, and I haven’t seen it in tennis. If she had to just play the men’s circuit, it would be an entirely different story.’

McEnroe stood by his comments in an interview with Late Show host Stephen Colbert: