"Let the best man win," the Russian billionaire said. "If he wins, I will crush him with the kickboxing throwdown."
Cuban, never one to back down from a challenge, was more than happy to respond.
In an email, Cuban warned the Nets owner about his wrestling skills dating back to his cameo in the WWE on "Monday Night Raw" back in 2009.
"He obviously didn't see me be the first in WWE history to put Sheamus on the mat," Cuban wrote. "He knows not what he gets himself into."
Prokhorov is the first one to joke around with the media, but if he loses Williams to the Mavs, Cuban will most definitely need to hire some extra security. The frisky Russian will be looking to show off his kickboxing skills against the fellow billionaire if he is forced to field a star-less team when the brand new Barclays Center opens in the fall.