Charlie Edwards initially thought he had lost his WBC flyweight title to Julio Cesar Martinez, but the fight was later ruled a 'no contest' due to an illegal punch.
Edwards was dropped by a third-round barrage but Martinez then hammered home a body shot to his floored opponent which went unpunished, and resulted in the end of the fight.
WBC president Mauricio Sulaiman announced the overturned result on a microphone to the cheering crowd after Martinez had already been announced as the new champion. Sulaiman also expects an immediate rematch.
"He did hurt me, I won't deny that, and that's why I took a knee. But it was the shot on the floor that put me away," Edwards said.
He added after Martinez's stoppage win was overturned: "I do believe that's the right decision. I took a knee for a purpose. He finished me off with a body shot. Cheaters never prosper."
Mexico's Martinez arrived with a reputation as a power-puncher having already stopped the previously-unbeaten Brit Andrew Selby to earn this fight.
He was thrashing Edwards with a serious of vicious shots in a disastrous third round for the champion.
Edwards sunk to a knee and looked in trouble when Martinez then punched him once more, illegally, although he was initially awarded a knockout victory before his celebrations were curtailed.