Five division world champion Floyd Mayweather Jr. was smiling on stage as he went face to face with Japanese kickboxing sensation Tenshin Nasukawa, during a ceremony at Saitama Super Arena in Saitama, north of Tokyo on Sunday.

Mayweather is scheduled to fight in a three-round exhibition match in Japan on New Year's Eve.

Neither kicking nor official results are part of the Rizin Fighting Federation match, but a knockout is possible under the special rules.

Nasukawa has promised that he's going to come out guns blazing, looking for a knockout victory.

"People in Japan, listen. I will take down Mayweather. You should look forward to it," Nasukawa said.

According to reports in Japan, Mayweather will earn as much as $20 million for the exhibition, which Mayweather does not seem worried about. He expects to easily outbox the young fighter, who has never competed in a bout with traditional boxing rules.

“It’s just another day. Another day like I wake up, take shower, put my clothes on," Mayweather said.

"Fighting is something I’ve done for over 30 years, so it’s just another day. I worry about entertaining and things, but once the bell rings, it’s always entertainment. So it is about having fun, going out there and doing my best.

"Me getting knocked out or me getting knocked down ... I don't worry about it at all. If that does happen, I mean that's entertainment. That's all we need to see. I mean, I’m sure he’s taking this fight extremely serious, he’s working out at this gym. (But) it’s just another day. I don’t have to work hard for three rounds. I can basically do three rounds in my sleep. So I don’t worry about that.”

Mayweather announced his retirement from the sport of boxing in August 2017, after securing a tenth round stoppage of UFC superstar Conor McGregor at the T-Mobile Arena in Las Vegas.