Australian boxer Anthony Mundine scored a sixth-round technical knockout win over American superstar Shane Mosley in Wednesday's World Boxing Association (WBA) international super welterweight title fight at the Sydney Super Dome, local media reported.

Mosley, 42 retired just ahead of the seventh round due to severe back spasms.

Mundine, 38, was well above Mosley before the American pulled out after the sixth round.

"My heart goes out to Shane, I know he's winner. He's not one to pull out for nothing. He's one of the greatest fighters to have ever lived," Mundine said after the win.

The victory secured Mundine the vacant WBA international super welterweight title.