Both of these figures are more popular now than Bobby Riggs and Billie Jean King were in their 1969 Battle of the Sexes historic match. Imagine how huge Johnny Mac vs Serena Battle of Sexes The Sequel would be?
Imagine how much it could attract attention and excitement to the sport.
Imagine how many new fans would be born.
Imagine how much money could be raised for charity.
Imagine how many sponsors and new tennis sponsors would want to get involved.
It all makes sense. So why doesn't it happen?
A few reasons. Serena has declined to respond to McEnroe's previous challenges. She obviously doesn't want any part of dealing with the pressures of defending the mythical title won by King.
McEnroe would love the adrenaline rush of such a high profile showdown - especially at Madison Square Garden - but he seems to understand Serena has no interest and has wisely refrained from pressuring or good-natured taunting her to play, which the media would surely interpret and portray as bullying.
But if Serena said "Game On!" to the idea, you can be 100% sure McEnroe would sign up it in a New York minute.
At the moment, the tennis industry is in a lull and could use a spark. McEnroe vs Serena could be just what the doctor ordered. Could public and media demand, buzz and chatter kickstart this Battle of the Sexes Part 2?