Tennis legend John McEnroe still believes he could defeat the top-ranked woman in the world, Serena Williams, even at age 56.

What also made headlines, however, was what McEnroe told Jimmy Kimmel about the embarrassment he would risk if the two actually played. 

"Serena, she's got a lot to lose by losing to an old fart like myself. And I've got a lot to lose, because if I lose to, God forbid, a woman, then I'm not allowed in any men's locker room for the next 15 years, or possibly the end of my life," he said.

"I believe that I could still take her," said McEnroe, recalling that Donald Trump offered them $1 million to play 15 years ago.

Williams, who will turn 34 next month, has won the past four Grand Slam tournaments and will go for the rare calendar-year sweep at the upcoming U.S. Open. 

Fox News contributor Meghan McCain said McEnroe's comment showed a lack of respect for Williams. 

"[She is] debatably the greatest female athlete of my generation. Have some respect, OK?" she said.

All were in agreement that Serena would come out on top if they played.

Watch the "Outnumbered" discussion above and the "Jimmy Kimmel Live" clip below.