SAITAMA –

Legendary former world champion Floyd Mayweather Jr. tamed Japanese kickboxing phenom Tenshin Nasukawa via technical knockout on Monday.

The special boxing exhibition, a dramatic conclusion to the Rizin 14 mixed martial arts event, took place before a New Year's Eve full house of 29,105 at Saitama Super Arena.

Capitalizing on his weight and size advantage, Mayweather, who had usually competed with a defensive style, pressed Nasukawa and knocked him down three times in the first round.

The 41-year-old American sent his opponent onto the canvas for the third time with 41 seconds left in the opening period.

The main event took place with less than an hour left in 2018 as the bell rang at about 11:20 p.m.

Mayweather had stressed that it would only be an exhibition, not a serious fight. The retired boxer told a Saturday news conference that he did not have to train for just three rounds and he would in fact be able to compete "in my sleep."

The undefeated star did not show up at the arena until about an hour and a half ahead of the match, concerning some organizers.

But after a lengthy introduction which featured a rendition of Japan's national anthem by legendary vocalist Gackt, Mayweather made short work of the plucky Nasukawa, smiling early in the first round but delivering a series of vicious blows to send the crowd to their feet.

"I'm still retired, I'm still 50-0, Tenshin is still undefeated, he's a true champion," Mayweather said, praising his opponent while noting the special nature of the exhibition. "He's a hell of a fighter and he's a great champion."

The exhibition also marked his first appearance outside of the U.S.

"Tokyo, Japan, you guys have been amazing," Mayweather said to cheers.