Naoya Inoue cemented his legacy with a unanimous decision win against fellow Japanese Junto Nakatani to retain his undisputed super-bantamweight status in Tokyo.
In what was billed as one of the biggest fights to take place on Japanese soil between two of boxing's top pound-for-pound fighters, Inoue, 33, once again rose to the occasion.
Inoue, a four-division world champion and undisputed in two weight classes, dominated early and adjusted later in the bout as the previously undefeated Nakatani, 28, grew into the contest.
Nakatani, who has held world titles in three divisions, suffered a cut above his left eye from an accidental clash of heads in the 10th round just as he was riding a wave of momentum.
Two judges scored it 116-112 and the third 115-113 at Tokyo Dome.
"This victory is very valuable for me because he is also a big pound-for-pound fighter," Inoue said.
"I will come back to Tokyo to fight for you again. Keep rooting for me."
Victory extends Inoue's perfect record to 33 victories, with 27 coming inside the distance.
Inoue's younger brother Takuma set the tone earlier on the card with a comprehensive points victory against Kazuto Ioka to defend his WBC bantamweight title.
Takuma urged the 55,000-strong crowd to keep the support going for his older sibling, and Naoya was roared to the ring as pyrotechnics lit up the stage.
The arena fell silent as the first half of the fight played out in tentative fashion, with both showing each other ultimate respect.
Inoue was left trying to solve the puzzle of how to bridge the distance to a rangier Nakatani, but, in his 28th successive world title bout, he used his vast ring IQ to find angles to get in and out as he primarily attacked the body.
Down on the scorecards, Nakatani began to engage in the second half of the bout as retired five-weight world champion Terence Crawford watched from ringside.
Southpaw Nakatani had wrestled back some control but was halted in his tracks when blood began to impair vision in his left eye following a clash of heads.
Inoue seized the opportunity to put his foot down and attacked with combinations in the final two rounds to punctuate another memorable victory.
After conquering the bantamweight division, Inoue moved up to super-bantamweight in July 2023 and became the undisputed champion later that year.
He has made seven successful defences of that status but has fast run out of serious challengers, leading to speculation that another divisional change could be on the cards.
Moving up to featherweight is an option, but the division lacks household names and a jump to super-featherweight is likely a step too far.
Dropping back down to the lower divisions appears to be the most likely route for Inoue, and preliminary talks are under way, external for a fight with pound-for-pound star Jesse 'Bam' Rodriguez.
American Rodriguez, 26, makes his bantamweight debut when he fights for the WBA title against Antonio Vargas on 13 June.
Rodriguez has reigned as unified champion at flyweight and super-flyweight, and boasts an undefeated 23-fight record - 16 inside the distance.
Inoue, who has fought five times in the past 15 months, said: "I have been so busy and had so many intensive days, so please give me a rest."
