(QHA) -

Wladimir Klitschko extended his 10-year winning run by beating Alex Leapai with a fifth-round knockout to retain his world heavyweight titles, BBC reports.

The Ukrainian, 38, scored a knock down after just over a minute in Oberhausen, Germany and was always in control.

Australia's Leapai had beaten Denis Boystov in November   to become the top WBO contender.

Leapai was aiming to be the first Australian to win the heavyweight title.

Klitschko noted it was not easy to win. “There are no easy opponents"- he said.

He added that the political turmoil in Ukraine made it hard to concentrate on training.

"I hope things will be stabilised"- he said.

Leapai was once on the books of rugby league team North Queensland Cowboys before turning to boxing, boasting 24 knockouts from his 30 professional fights.

Klitschko is unbeaten since his 2004 loss to Lamon Brewster, with an 80% knockout rate from his 64 professional fights.