A light-heavyweight fight between Britons Ben Whittaker and Liam Cameron has ended in a draw after both crashed out of the ring, while Australians Jai Opetaia and Skye Nicolson both retained their belts in Riyadh, Saudi Arabia.

Whittaker left the arena in a wheelchair and was taken to hospital for scans to his injured leg after he and Cameron grappled onto the ropes and tumbled over the top.

Cameron was sprawled on Whittaker as they fell on the outer canvas towards the end of the fifth round, with the latter unable to get up.

Cameron, 33, said the highly touted Whittaker pulled the pair over the ropes in the fifth round.

"He was holding a lot, the referee could have taken a point off," he said.

The bout was abandoned due to accidental injury and declared a technical split draw, with Whittaker 58-57 on one scorecard and Cameron ahead by the same score on another with the third tied 58-58.

But Whittaker, who took an undefeated 8-0 record into the fight against a more experienced opponent, appeared to be flagging, with one commentator saying he was "far, far too easy to hit".

"Boy, we're learning a lot about Whittaker here, and it's not good stuff," another commentator said.

"He's getting hit by a much slower fighter."

And it was then that the pair tumbled out of the ring.

"Whoa, wait a minute, they've gone royal rumble WWE-style [over the ropes]," the commentator added.

A disappointed Cameron was adamant he was on top and the win was "imminent".

"I was just starting to put my hard shots together," he told Boxing News.

"Ben was knackered from the second round, I really don't know what was up with him. It was kind of mad; he was done from round two. He gave me his last hurrah that round.

"I was saying to him 'it's only the fifth round and you're knackered, Ben', but he kept on holding me, hitting me low."

Later in Riyadh, Nicolson beat Englishwoman Raven Chapman to retain her WBC featherweight belt in the first women's world title fight in Saudi Arabia.

Nicolson utterly dominated the bout, winning a unanimous decision scored 99-91 on one judge's card and 98-92 on the other two.

Meanwhile, Opetaia did not leave his fight in the judges' hands as he kept his cruiserweight world titles, beating Jack Massey via technical knockout when the Englishman's team threw in the towel in the sixth round.

The fights were on the undercard for the undisputed light-heavyweight world title bout between WBA champion Dmitry Bivol and Artur Beterbiev, the WBC, WBO, IBF champion.

Beterbiev edged Bivol by majority decision.

ABC/Reuters