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Since defeating Conor McGregor in a boxing ring last year, Floyd Mayweather has continuously teased participating in a mixed martial arts fight, regularly suggesting he would take on McGregor in a rematch or set a bout with Khabib Nurmagomedov. Though many took Mayweather's MMA aspirations as a bluff, it looks like he may actually back up his talk … just not against any UFC competition.

Mayweather announced at a Sunday night press conference that he will compete for RIZIN Fighting Federation in a bout against Tenshin Nasukawa, an undefeated kickboxer. RIZIN is a Japanese promotion, and the "Super Challenge" fight between the two will take place at RIZIN 14 on Monday, Dec. 31 in Saitama, Japan.

It was not specified whether Mayweather and Nasukawa will box, kickbox or participate in MMA, though Mayweather revealed at the press conference that those details will be worked out within the coming weeks. 

Nasukawa, called "perhaps the best combat sports prospect [Japan] has ever seen" in the press release for the fight, is 27-0. Turning 20 just a few months ago, he is half the age of Mayweather, 41, who has only fought once since 2015. Nasukawa has won four fights this year alone.

Mayweather, who claims to have earned $100 million from his McGregor fight, teased the bout with Nasukawa earlier Sunday by taking an Instagram photo in which he was wearing kickboxing gloves. Mayweather (50-0) has held world titles in five different weight classes and won the seven fights prior to his bout with McGregor by decision.

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While some may refer to all of this as a one-time publicity stunt to be pulled during the promotion's biggest night of the year, it actually comes across as the beginning of a business relationship between the two parties -- if Sunday's press conference is any indication. 

RIZIN promoter Nobuyuki Sakakibara first alluded to the idea that some sort of partnership has formed while speaking to the media on Sunday. 

"I think my shortest answer to that is the fact that now we are aligned to achieve something together, and that is hitting a new challenge, taking a step forward to whatever wonderful thing that we can create together," Sakakibara said (via MMA Fighting). 

Mayweather would follow up by giving his best form of confirmation that there are more plans ahead in the future, and this venture into the MMA business -- whatever that may end up entailing with this initial bout -- is just the beginning. 

"Rizin has done a remarkable job with the fighters," Mayweather said. "I look forward to giving you guys entertainment come Dec. 31, but my relationship with Rizin, it doesn't stop just here. I look forward to taking this worldwide." 

There's no telling what the translation to Mayweather's explanation actually is, as we're not even aware of what variation of combat sports he'll be taking part in come New Year's Eve. But however you may view Mayweather the person, his business acumen speaks for itself, which undoubtedly has RIZIN officials optimistic. 

We're just going to have to wait and see how the events of the coming weeks unfold before we can get a better outlook of just what exactly the self-proclaimed promotional king has cooked up.