Kosei Tanaka added to his impressive collection of belts and is now a champion at 115lbs having won belts at 105, 108 and 112.
The new WBO super flyweight champion won the vacant title with a solid victory over Mexican co-challenger Christian Bacasegua, flooring the Mexican in round eight and earning the decision on all three scorecards by margins of 116-111, 117-110, and 119-108.
Bacasegua was tactically smart early on and he started with a sense of purpose and aggression, but the tide gradually began to turn and Tanaka took over.
Tanaka really began to get on top in the eighth, with Bacasegua scrappily touching down after shipping a barrage of blows up and downstairs.
The momentum had shifted, however, and 28-year-old Tanaka was starting to find a home for his right uppercut, lancing Bacasegua with straight right hands and Bacasegua sported a cut and an angry lump above his right eye as the scars of battle began to show themselves.
Bacasegua, 26, was still in there pitching, but Tanaka was able to step to the side and let his hands go and he could now time Bacasegua, while the Mexican was more straightforward and worked straight lines.
Tanaka closed the 11th strong, rattling and seemingly hurting Bacasegua to the body and he carried on in the same manner in the final round. Courageous Bacasegua showed incredible heart to stand and fight but by this point there was only one winner of a quality fight.
Pre-fight favourite Tanaka is now 20-1 (11KO) and Christian Bacasegua drops to 22-5-2 (9 KOs).
Tanaka had previously attempted to capture super flyweight gold before but was defeated by Kazuto Ioka in 2022, who stopped him in the eighth-round of his only loss – for the same belt.
“This belt was everything I wanted tonight,” said Tanaka. “These past three years have been a rough time for me since I was defeated and I’m happy to be where I am tonight.”
Tanaka saluted the crowd and said he wanted a rematch with the brilliant Ioka, but that first he wanted to fight IBF champion Fernando Martinez.
Riku Masuda got things under way with a terrific southpaw left to the body that crumpled Jonas Sultan to the deck in the first round.
Filipino Sultan tried to get back up, but the pain took him back down again and he was counted out at 2:21
The was a bone-crunching body shot and will be in the highlight reel packages come the end of the year.
Masuda improved to 4-1 (4 KOs). Sultan falls to 19-6 and was stopped for the first time.
Ren Kobayashi scored a fourth-round stoppage of Kensho Oyamada in a battle of featherweight debutants.
