Ukrainian champion Oleksandr Usyk has knocked out Britain's Daniel Dubois in the ninth round to retain his WBA, WBO and IBF heavyweight world titles.

Usyk, fighting in front of a partisan 40,000-strong crowd in Poland, knocked Dubois down at the end of round eight.

In the next round, a tiring Dubois was sent to the canvas again and failed to beat the count.

Usyk took almost four minutes to recover in round five after being hit with a punch that the referee deemed to be low.

He insisted he should be the heavyweight world champion after being "cheated out".

[Source: BBC Sports]