A bloodied Tim Tszyu has been cruelly denied in his quest to emulate his legendary father Kostya and become a unified world boxing champion after a sapping loss to towering American Sebastian Fundora.

Suffering his first defeat in 25 fights, Tszyu surrendered his WBO super welterweight belt and the vacant WBC strap at T-Mobile Arena in Las Vegas, missing his chance to take his place among the sport’s elite.

Tszyu lost the fight in a split decision, with the judges scoring the fight 116 -112, 115-113, 112-116 in favour of Fundora.

The unlucky Australian’s fight derailed at the end of the second round when he walked into the elbow of 197cm Fundora, opening up a huge gash on his head. But he was gracious in defeat.

“Look, I told you, I’m an old throwback fighter whatever circumstances. I couldn’t see but all credit belongs to the man who won tonight,” Tszyu said. “These things happen. The momentum was rolling. I was swinging hard in the first rounds and then ‘boom’, you’re blinded completely.

“But, look, this is boxing. This is part of the sport and it happens.

“Congratulations to Fundora – he’s the new king at 154 (pounds).”

The world champion had dominated the opening exchanges, putting his tall-timber opponent on the back foot with some heavy right-hand blows. Despite blood pouring down his face, Tszyu was cleared to continue by the fight doctor but Fundora took advantage of the Australian’s lack of vision to level the score.

With both fighters covered in blood, with Fundora’s nose also gushing, the Australian continued to search for a way to bring the battle to an early end.

Fundora played it smart by trying to attack Tszyu’s head while the Sydney warrior, using his gloves to wipe the blood from his eyes, was unable to connect in his usual fashion. With Fundora edging ahead, the doctor again checked the cut at the start of the seventh round but gave the green light for it to go on.

Like a gladiator, Tszyu battled on as he hunted a knockout blow but hindered by the blood flow he was unable to stop the Californian.

Fundora’s win sees him join his younger sister Gabriela as a world champion after she captured the IBF flyweight world title earlier this year.

Tszyu was attempting for he and Kostya to join Leon and Corey Spinks as only the second father-and-son duo to become unified world boxing champions.

He was also looking to set up a mega fight against either pound-for-pound king Terence Crawford or former unified welterweight champion Errol Spence Jr, with a pay cheque of $US10 million ($A15.3 million) on the table.

“Look, I’ll bounce back,” Tszyu said. “I showed up still, no matter what (injury I had), and I always bring the fight.

“I was given one week (to prepare), no excuses, but I’ll fight whoever, whenever. Even Errol Spence, who’s here. I’ll fight him as well. Even Terrence Crawford, man. You want a good scrap, You know who to call?”

Tszyu’s defeat ended a miserable 24 hours for Australian boxers with Liam Wilson and Michael Zerafa also losing their world-title fights on a huge weekend in the US.