Kyouken Densetsu Crazy Knuckle

Story is about a martial artist called Zado who wants to the be the world's most powerful martial artist. To do that, he is collecting little fragments that will lead to the secret of the ultimate martial arts skill. In order to learn the skill, he has to defeat the people who holds these individual fragment. However, Zado's most-trusted henchmen took all the fragments and learn the ultimate skill himself and defeats Zado. To regain his dignity, Zado has to defeat his henchman in the battle ring.

[From Anime Densetsu]