Oleksandr Usyk beats Britain's Anthony Joshua on a surprise split points decision after 12 hard rounds to retain his WBA, WBO, IBF and IBO world heavyweight boxing belts in Jeddah.

The fight was watched on free-to-air TV by millions of Ukrainians living under the Russian offensive.
The fight was watched on free-to-air TV by millions of Ukrainians living under the Russian offensive. (AFP)

Ukraine's Oleksandr Usyk has won his rematch against Anthony Joshua by split decision to retain his world heavyweight boxing titles in just his fourth fight in the division in Saudi Arabia.

Usyk, 35, who dismantled the defending champion in London last year, faced an improved Joshua on Sunday but outboxed him once again to set up a potential unification bout with Britain's Tyson Fury.

"I want to thank God for the help that he gave me today," Usyk told the crowd at the 12,000-seat King Abdullah Sports City Arena in Jeddah.

"I give this victory to my country, to my family, to my team and to all the military who are defending the country," he added.

READ MORE: Fury will only return to arena for unification fight against Usyk: wife

The fight was watched on free-to-air TV by millions of Ukrainians living under the Russian offensive. 

Usyk signed up to fight for his country before accepting the rematch.

An angered Joshua peppered his post-match speech with expletives despite the presence of Crown Prince Mohammed bin Salman.

The judges scored it 113-115, 115-113 and 116-112 for Usyk as Joshua narrowed the gap but was still found wanting.

Joshua, the 6ft 6ins two-time world champion is left staring at an impasse in his career after his third defeat in his 12th straight title fight left him with figures of 24-3-0.

Joshua, accused of hesitancy in their first fight in London, was the early aggressor by round two as he repeatedly landed his big right hand.

READ MORE: Usyk dethrones Joshua to claim world heavyweight titles

Source: AFP