Floyd Mayweather Jnr

Rizin Fighting Federation announced a bout between Mayweather and Nasukawa for New Year's Eve earlier this week, with the two fighters appearing alongside one another at a media event in Tokyo.

Yet boxer Mayweather, now back in the United States, says he never agreed to fight Nasukawa and understood that he would have an exhibition bout against an unnamed Rizin fighter for "a very large fee".

In August last year, Conor McGregor swapped the octagon for the boxing ring to take on the legendary American, who won in the 10th round to extend his perfect record to 50-0.

Having retired from boxing, Mayweather appears set to make McGregor's move in reverse and try his hand at mixed martial arts.

Last week, Mayweather confirmed he is to begin MMA training with UFC welterweight champion Tyron Woodley while he has previously teased a potential rematch with McGregor on social media.