Anthony Mundine scored a sixth-round technical knockout over Shane Mosley on Wednesday in their WBA international super welterweight title fight, the first time the American has failed to go the distance.
The 42-year-old Mosley (47-9-1) retired just ahead of the seventh round due to back spasms.
He said he would decide after he returns to the U.S. whether he would retire.
Mundine, 38, improved to 45-5 with 26 knockouts.
Handlers for Mundine said before the fight they hoped a win would give the 10th-ranked WBA contender a fight against Floyd Mayweather.
The fight was delayed for five weeks over financial issues.