Naoya Inoue became the first undisputed bantamweight champion in 50 years when he took the WBO title off Britain’s Paul Butler with a commanding performance in Tokyo.

Butler, 34, was given a lesson by the 29-year-old from Japan, who dominated throughout until he ended the contest with a with a right hand to the body followed by a solid left hook and a barrage of unanswered punches that floored Butler.

It was Inoue’s 21st career knockout and it guaranteed a slice of history, with no bantamweight having held all of the titles in the four-belt era. “This is the greatest moment [of my career],” Inoue said after the fight.

Inoue is likely to move up the weight divisions now, having already won world titles at super-flyweight and light-flyweight. The Japanese boxer was competing in his 19th consecutive world title bout and remains unbeaten in 24 professional fights.