Australian Kostya Tszyu successfully defended his world super lightweight boxing title against American Jesse James Leija.

Leija failed to answer the bell for the start of the seventh round in Melbourne, handing Russian-born Tszyu his 30th win in 32 fights and his 14th title fight win.

Tszyu, 33, remains the undisputed super lightweight champion and holds WBC, WBA and IBF belts.

I am sure it is busted but to what extent I don't know, I'm not a doctor James Leija

He has one career loss - to American Vince Phillips - and one no-contest against Puerto Rican Leonardo Mas.

Leija, who had a nasty cut in the corner of his right eye, said he had difficulty retaining his balance after damaging his right ear drum in the fourth or fifth round.

"I am sure it is busted but to what extent I don't know, I'm not a doctor," he said.

Leija had started brightly and was ahead on the judges' cards after three rounds.

However, Tszyu then used his superior power to wear his opponent down and is next expected to have a mandatory defence against either Gianluca Branco or Arturo Gatti.