Five division world champion Floyd Mayweather, 41-years-old, scored a brutal first-round knockout victory in a mismatched exhibition fight against Tenshin Nasukawa in Saitama.

Mayweather rocked up to the arena late, causing a 90-minute delay to the scheduled fight time, with a flooded hotel lobby blamed for his delayed arrival.

But Mayweather soon made up for lost time, knocking down his opponent twice before flooring him for a third and final time with a fierce right as the three-round exhibition, which was truthfully a pretty farcical affair, came to an abrupt end with around 40 seconds left in the first.

Nasukawa, an undefeated kickboxing sensation who had vowed to “take down Mayweather” was left in tears in the ring but was hailed by his opponent, who claimed on Instagram he will earn $9 million for the bout.

“I want to say thank you to Tenshin, it’s about entertainment,” he said in the ring. “Tenshin is still undefeated, I did this just to entertain the fans.

Mayweather floored his opponent three times in as many minutes to secure a swift victory.

“I said, ‘Why not?’. I’m still retired, still 50-0. Tenshin is a true champion and a hell of a fighter. Tenshin, hold your head up high, I want fans around the world to support Tenshin, he’s a great guy and a great champion.”

Afterwards,  Nasukawa stated that he was reckless in the fight and Mayweather made him pay for it.

"He is first class. It was a challenge that I fought for and I was reckless, and the result was a defeat, but I don't regret it. I couldn't reach Mayweather even in my 20 years but I went out there with courage," Nasukawa said.

"Thank you Mayweather for fighting, and thank you to everyone for your support. I will never be able to thank all of you but I will continue to learn from this, thank you for this year."