When Floyd Mayweather announced that he is set to make a fight return in Tokyo, Japan - questions were automatically asked.

Mayweather is set to meet undefeated Japanese fighter Tenshin Nasukawa, on December 31, with MMA promotions RIZIN Fight Federation promoting the event.

The 20-year-old Nasukawa is undefeated in his 27 kickboxing bouts winning 26 by knockout while he is also 4-0 as an MMA fighter.

Mayweather is confirmed to fight Nasukawa - but that’s all that is known so far, with the ruleset, gloves, rounds and weight all yet to be finalised and agreed.

However, many believe Mayweather won’t compete in anything other than straight boxing rules - something he is 50-0 in winning world titles in five weights.

One man who shares this view is UFC commentator and Martial Arts expert Joe Rogan, as he took to Instagram to share his views on the fight and Nasukawa.

Joe Rogan on Nasukawa and the ruleset 

“I don’t know what kind of ‘special rules’ they’re supposed to be fighting under.” Rogan wrote.

“But I just like the fact that it’s going to happen and that people get to google Tenshin’s name and see some of his fights.

“He’s a true striking genius. I doubt Floyd is going to agree to any rules that allow Tenshin to kick, but if he does it could be a terrible night for him.

“This kid is the truth.”

Rogan is right - it takes just a YouTube search to understand what kind of threat and talent Nasukawa possesses, with both his hands, elbows and legs.

This isn't the first time Mayweather will compete in a crossover bout, as last year the undefeated American took on UFC star Conor McGregor in what was widely regarded a money-grabbing showdown for both parties.

Mayweather would halt McGregor after 10 rounds, and after an estimated $400 million was generated and 4.4m PPV’s bought in the US - a rematch has never been too far away from rumour mill.

However, Mayweather has now shocked the world and opted for an unknown name to many in the fight world.

As Mayweather prepares to face his second consecutive southpaw mixed martial artist, will Japan see a mixed rules exhibition, or a straight boxing match?