SYDNEY -- Former rugby league player Anthony Mundine scored a sixth-round technical knockout over Shane Mosley in their WBA international super welterweight title fight on Wednesday, the first time the American has been stopped inside the distance.

Mosley, a 42-year-old with a record of 47-9-1, decided to retire before the seventh round due to back spasms. He said he would decide after he returns to the U.S. whether he would retire.

"What's done is done," Mosley said when asked whether he would fight again.

The 38-year-old Mundine improved to 45-5 with 26 knockouts at Homebush in western Sydney. Mundine was leading 58-56 on two cards and 60-55 on the third.

"I was in killer mode, but my heart goes out to Shane, I know he's a winner," Mundine said. "He's not one to pull out for nothing. He's one of the greatest fighters to have ever lived."

The fight was delayed for five weeks over financial issues.

The contest was refereed by American Raul Caiz Sr., who has controlled two of Mundine's past bouts and one of Mosley's. Caiz stopped the fight on the recommendation of fight doctor Lou Lewis.

In another bout, former Canberra Raiders rugby league halfback Blake Ferguson lost a four-round unanimous heavyweight points decision to Luke Turner.

Ferguson, who finished 39-37 behind on all three cards, was released by Canberra in September after failing to appear before the board of directors following breaches of the club's code of conduct.

His rugby league career remains in doubt pending the findings of the National Rugby League integrity unit. He has also had to deal with two court cases regarding charges of indecent assault and driving indiscretions.