On October 10, 2026, at Wintrust Arena in Chicago, Sergio Mendoza pulled off one of the year's biggest upsets by stopping Ricardo Sandoval, the unified WBA and WBC flyweight champion, via TKO in the fifth round. Featured in the co-main event of Schofield vs. Bahdi on a Golden Boy card broadcast by DAZN, the Mexican southpaw brought Sandoval's reign to an end at 1 minute 46 seconds of the fifth round, when referee Mark Nelson stepped in. Called up on short notice to replace the injured Oscar Collazo, Mendoza was clearly the underdog: Sandoval was priced at 7-to-1, despite returning from fifteen months out of the ring. By the end of the night, Mendoza had improved his record to 28-1 (24 KOs), while Sandoval fell to 27-3 (18 KOs).
The fight was decided by three knockdowns. As early as the second round, Mendoza sent Sandoval to the canvas twice, first with a right hook and then with a left uppercut, immediately turning the threat posed by the late replacement into a tangible reality. Sandoval held on, but never managed to regain control, and in the fifth round a counter right hook sent him back to the canvas before Mark Nelson stopped the contest. For Sandoval, the defeat was unprecedented: in thirty professional fights, he had never been stopped. He therefore loses both belts in circumstances that leave no room for debate, in stark contrast to the manner in which he had won them just over a year earlier.
Mendoza's journey makes the performance even more remarkable. Six months earlier, on April 13, 2026, at Korakuen Hall in Tokyo, he had been knocked out in the second round by Thanongsak Simsri in a challenge for the IBF light flyweight title, and nothing about that defeat suggested he would so quickly become a unified champion at flyweight. He leaves Chicago with the WBA and WBC belts, two of the division's four major titles, and suddenly establishes himself among the leading names at 112 pounds. “I'm in shock right now… Viva Mexico!”, he exclaimed after the fight, dedicating his victory to his recently deceased brother. Oscar De La Hoya described it as an “Amazing surprise” and an “Incredible KO of Sandoval”, words that sum up a night in which a last-minute replacement overturned every prediction.
At BoxingP4P, we welcome this result with genuine satisfaction, and we make no apologies for it. On July 30, 2025, at Yokohama Buntai, Sandoval had claimed the WBA and WBC titles from Kenshiro Teraji via split decision, with scorecards of 117-110 and 115-112 in his favor against 114-113 for Teraji, even though the Japanese fighter had knocked him down during the bout. In Japan, the 117-110 scorecard was criticized for its margin. In our view, Teraji did not deserve to lose that night, and we consider the decision a robbery. This is an editorial judgment, and we are not suggesting that Chicago officially sets the record straight on Yokohama: Mendoza won on his own merits, with three knockdowns and a clear stoppage. But seeing Sandoval lose the belts he had won through a verdict we considered unjust, in an upset of his own, feels logical, almost fair.
The outcome in Chicago, however, is unequivocal. Sergio Mendoza defeated the unified flyweight champion before the final bell, and this time there was no need for a controversial scorecard or a debate over the points to separate the two men. The division has a new WBA and WBC champion, while Sandoval, stripped of his titles and stopped for the first time in his career, will have to rebuild what his disputed victory in Yokohama never truly gave him: unquestionable legitimacy.
