Tenshin Nasukawa Says He's Not Sure Floyd Mayweather Can 'Keep Up' in IG Post

Tenshin Nasukawa isn't lacking confidence ahead of his upcoming exhibition fight with Floyd Mayweather Jr.

The 20-year-old Nasukawa posted a training video Wednesday on Instagram and accompanied it with the caption: "I'm not sure if a 42 year old can react to these."

Rizin Fighting Federation head Nobuyuki Sakakibara told the Associated Press (h/t ABC News) this month that the Dec. 31 fight between Nasukawa and Mayweather will be a three-round exhibition, and while knockouts will be allowed, there will likely be no decision granted if they go the distance.

After taking part in a press conference last month, Mayweather made a post in Instagramearlier this month saying he "never agreed" to fight Nasukawa.

He also said that he had been led to believe he was taking part in an exhibition in front of a "small group of wealthy spectators" that wouldn't be internationally televised.

While Mayweather's statement left the state of the fight in question, he spoke to TMZSports two weeks ago and said, "We're gonna make it happen."

Mayweather also said it would be a boxing exhibition with no kicking.

Sakakibara noted that the fight won't count on the records of either fighter, and while he did not rule out a "last-minute cancellation," the event is scheduled to be held at the Saitama Super Arena near Tokyo on New Year's Eve.

The 41-year-old Mayweather is a perfect 50-0 as a professional boxer, but he is technically retired and hasn't boxed since beating Conor McGregor by 10th-round knockout last year.

Nasukawa is 27-0 as a kickboxer and 4-0 in professional mixed martial arts, but he has never taken part in a pro boxing match.

Given the rules of his encounter with Mayweather, that won't officially change, but he has a chance to make a major statement if he can rattle the legendary boxer.