An emotional Oleksandr Usyk shed tears for his late father after crowning a brilliant career by becoming boxing's first four-belt undisputed heavyweight world champion on Sunday.

The 37-year-old Ukrainian won a split decision against Britain's Tyson Fury in Riyadh in the first heavyweight unification fight since 1999.

The former European and world amateur champion, Olympic gold medallist and undisputed cruiserweight champ -- still undefeated as a professional -- now adds the ultimate boxing crown.

Afterwards Usyk, who needed four stitches to a cut above his right eye, and who was headed to hospital for a scan of his jaw, remembered his father, who died shortly after his Olympic victory in 2012.

"I miss my father," he said, wiping his tears with his T-shirt. "I know he's here."

Usyk has missed children's birthdays and even the birth of his daughter during his eight-month camp for the Fury fight, originally scheduled for February before the Briton suffered a cut in training.

His promoter Alex Krassyuk believed that Usyk was denied a knock-out victory when the referee stepped in as Fury looked about to hit the deck in round nine.

"I believe the referee saved Tyson from a knock-out and stole the ninth-round knock-out, which should have happened," Krassyuk said.

But Usyk said: "No knock-out, no problem."

"I don't think about it because we had a win."