Floyd Mayweather to fight kickboxer Tenshin in Japanese fighting league RIZIN!

Floyd Mayweather has taken his next fight, but it won’t be against a familiar UFC superstar. (AP)

Floyd Mayweather’s next crossover fight won’t be against Conor McGregor or Khabib Nurmagomedov.

The undefeated boxer will take on Japanese kickboxing sensation Tenshin Nasukawa in what’s being called a super bout challenge.

The fight was announced early Monday at a news conference in Japan.

Boxing, MMA, kickboxing?

Rules for the fight weren’t announced. We’re not sure if the fight will be MMA, kickboxing or boxing. Mayweather said in the news conference that those details are still being hammered out.

“As far as the weight class and the rules, we’ll get that situated in the next few weeks,” Mayweather said.

Fight to take place New Year’s Eve

What’s not being hammered out is that a fight of some sort will take place between two undefeated fighters.

Mayweather is 50-0 as a boxer with 21 knockouts, and most recently defeated McGregor when McGregor transitioned from the UFC Octagon to the boxing ring.

Tenshin is 27-0 as a kickboxer with 21 knockouts.

The fight will take place on Dec. 31 at the Saitama Super Arena in Japan.