'Respect me and my privacy' - Serena Williams hits back at John McEnroe comments

US tennis star Serena Williams has lashed out at John McEnroe asking him for "respect" after the seven-times grand slam champion said the soon to be mother would be ranked "like 700 in the world" if she had to play on the men's circuit.

In an interview with National Public Radio on Sunday, McEnroe said the 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. 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, said McEnroe.

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, she wrote.

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.

Williams has won the most grand slam singles titles in the professional era, five more than Swiss Roger Federer, the most prolific winner in the men's game.