Tim Tszyu has suffered another devastating setback, losing once again to American Sebastian Fundora in the pair’s much-hyped world-title rematch in Las Vegas.

Tszyu had been hunting redemption after losing a split-decision bloodbath to Fundora 16 months ago.

Instead Australia’s former WBO super-welterweight world champ will return to Sydney with his international career at another crossroad following a despairing seventh-round TKO defeat.

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Saturday night’s loss at the MGM Grand’s Garden Arena was the 30-year-old’s third from his past four bouts, after going unbeaten for his first 24 professional fights.

Tszyu also endured a crushing world-title loss last year to big-hitting Russian Bakhram Murtazaliev before Fundora sportingly offered him a rematch after the Sydney slayer knocked out fellow American Joey Spencer in March.

Tszyu (25-3, 18KOs) may even consider a move up to the light-middleweight ranks, or hope Keith Thurman lives up to his word after the US star called him out after slaying Brock Jarvis earlier this year in Sydney.

More immediately, Tszyu must digest another sapping defeat at the hands of “The Towering Inferno”.

Last time around against his gangling 197cm opponent, Tszyu had to fight for 10 rounds half-blinded after walking into Fundora’s elbow and suffering an horrific cut to an artery at the top of his head.

In the return bout, Tszyu fought with more patience but couldn’t stay with the near two-metre tall rival.

Fundora made a spectacular start, dropping Tszyu in the opening round with a thunderous straight left to the head.

Tszyu’s cut man Mark Gambin was again under immense pressure after Fundora landed a flurry of punches to open up a nasty wound above the Australian’s right eye in the second round.

Struggling to cope with Fundora’s massive height and reach advantage, Tszyu looked in peril before catching the American with a huge over-hand right in round four.

But the Californian, the tallest world champion in all of boxing — continued to throw and land more punches than Tszyu.

Tszyu needed to conjure something special.

Showing supreme courage to stay in the contest, Tszyu found some joy with his body shots before the fight exploded in a ferocious round seven.

Despite hurting Fundora and maybe even breaking the champion’s nose, Tszyu told his corner he could not return for round eight.

“Holy s***, Tim Tszyu quits before the eighth,” one boxing fan wrote on X.

“Never thought I’d see the day he refused to continue fighting. Man has the heart of a lion, but Sebastian Fundora was just too good.”

Fundora is about to start a six-year engineering degree at Harvard University but Tszyu graciously said his vanquisher already is fully qualified in the sweet science.

“He’s one tough motherf*****,” Tszyu said after the fight.

“I tried to give it everything, but I just couldn’t do it and victory belongs to Sebastian Fundora, the best 154-pounder on the planet right now.

“He was just a better man. He’s a better man.

“He’s very hard to land. He’s tall as f*** and sometimes I feel like I was shadow boxing with myself.

“But it is what it is. Congratulations to Fundora and his team.”