John McEnroe believes Serena Williams would not be able to compete with male tennis players.
McEnroe claims Williams, a winner of 23 major titles would struggle on the men’s tour and would rank 700th in the World.
"If she played the men's circuit she'd be, like, 700 in the world," he said in an interview with NPR Radio.
The seven-time Grand Slam champion McEnroe insisted that he meant no disrespect in his comments, and claimed Williams is the greatest female player of all time.
He doesn't feel that would count for much against one of her male counterparts:
"That doesn't mean I don't think Serena is an incredible player. I do, but the reality of what would happen would be I think something that perhaps it'd be a little higher, perhaps it'd be a little lower.
"On a given day Serena could beat some players. I believe she's so incredibly strong mentally that she could overcome some situations where players would choke.
"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."