'I was the one underestimating him': Nasukawa opens up after crushing Mayweather defeat

Tenshin Nasukawa has spoken for the first time since his humiliating first-round TKO at the hands of Floyd Mayweather at Rizin 14.

The Japanese kickboxing world champion carried an undefeated record into the ring to face Mayweather on New Year's Eve, but was badly outgunned by the 50-0 boxer in what turned out to be a horrible mismatch in Saitama.

Mayweather, 41, decked 20-year-old Nasukawa three times as he stopped the Japanese fighter in just 140 seconds in their three-round exhibition boxing bout, leaving the young star in tears.

Despite the crushing nature of his defeat to Mayweather, Nasukawa's undefeated kickboxing record remains intact, and he insists he has no regrets over taking the high-profile exhibition bout.

"I have worked hard with a big dream in the combat world. Karate, Kickboxing, MMA and Boxing. When I first got the offer I took it in a flash," he admitted in an Instagram post.

"I thought this was an opportunity of a lifetime, and although there were significant differences in accomplishments and weight classes, I felt that I must not run and take on the challenge."

The 20-year-old admitted the defeat hurt, and also confessed that perhaps the opportunity came before he was ready to truly take advantage of it.

"The days since the fight was confirmed have been enjoyable but with concerns," he continued.

"I am disappointed at myself since I thought I could have done better. But I will face the facts and will continue to take on any challenge.

"I learned that I didn't work hard enough to earn this opportunity, and I will use this defeat to improve myself and move forward this year."

Nasukawa also took the opportunity to praise Mayweather and vowed to come back even better as he looks to build on his already-impressive martial arts career.

"Despite all the things that happened leading up to the fight, I came to realize how truly great Mayweather was.

"I was the one underestimating him. I promise to make it to that level.

"It may take some time for me to become the man to haul the industry on my shoulders, but please continue to support me!

"Everybody who work to make this fight happen, thank you very much. Mr. Mayweather, thank you very much."