Mosley pulls out of Mundine fight
Boxer 'Sugar' Shane Mosley (R) greets fans at the official weigh-in for boxers Floyd Mayweather and Canelo Alvarez in Las Vegas on September 13, 2013
The pair were due to face off in Sydney on Wednesday but Mosley pulled out just hours ahead of the weigh-in, leaving Mundine demanding answers.
"I'm very disappointed with this turn of events because I was planning on making a big statement by beating Mundine, but I was left with no choice but to withdraw," Mosley said in a statement.
Golden Boy Promotions chief executive Richard Schaefer said their fighter had no other option after the remaining US$700,000 of his $1 million purse was not paid as required under the terms of the contract by 5:00 pm on Monday.
It is a huge blow for Mundine, a former rugby league footballer, as it was to be his first bout since losing an IBF world middleweight title fight to fellow Australian and arch-rival Daniel Geale in January.
"I've just been told that they have cancelled the fight!," Mundine wrote on his Facebook page.
"The promoter needs to tell us all what happened.... I'm very disappointed for fans."
A victory for Mundine would have given him much-needed leverage in the United States to secure some high-profile fights, but those hopes are now in ruins unless a way can be found to resurrect the contest in the future.
Mosley, who has won five world titles in three weight classes, announced his retirement in June last year after he lost a unanimous decision to junior middleweight champ Saul "Canelo" Alvarez of Mexico.
But the 42-year-old returned to the ring in May, beating Pablo Cesar Cano by unanimous decision to win the vacant WBC international welterweight title in Mexico.