Floyd Mayweather to Fight Kickboxer Tenshin Nasukawa at Rizin FF 14

Floyd Mayweather Jr. will surprisingly make his return to the spotlight with a bout against Japanese kickboxer Tenshin Nasukawa, according to Dan Rafael of ESPN.com.

It is not yet known whether the fight will be under boxing or mixed martial arts rules.

According to Ariel Helwani of ESPN, the rules are still being worked out:

The bout is scheduled for Dec. 31 at Saitama Super Arena in Saitama, Japan, as part of the Rizin 14 pay-per-view.  

Mayweather is one of the best boxers of all time, posting a 50-0 record in his professional career. While he did compete against an MMA fighter in his last bout—a knockout win over Connor McGregor—it was under boxing rules.

It was also his only match since 2015, as he's presumably been retired from competition.

However, he teased a move to MMA in January, showing his training inside the Octagon:

Although this led to plenty of speculation about a rematch against McGregor or a bout with Khabib Nurmagomedov, it appears Mayweather is throwing everyone for a loop by competing in the Rizin Fighting Federation.

Nasukawa is only 20 years old, but he has already earned a reputation as one of the top competitors in the sport. According to Tom Taylor of BJPenn.com, he is 4-0 in his professional MMA career but is already 27-0 as a kickboxer.

Depending on the rules, this could be a difficult bout for Mayweather instead of just an easy payday.