Tim Tszyu's international boxing career lay in tatters following a savage and sobering world-title loss to Bakhram Murtazaliev in Florida.

Having seen enough of an onslaught from Murtazaliev, Tszyu's younger brother Nikita mercifully threw the towel into the ring less than two minutes into the third round of Sunday's much-hyped IBF super-welterweight showdown.

Murtazaliev had floored Tszyu three times in the second round alone with some ferocious punching, before the official doctor intervened after the referee refused to stop the fight.

But there was no coming back when the Chechen champion delivered another massive blow to send a dazed and seemingly senseless Tszyu crashing to the canvas for a fourth time to improve his undefeated record to 23-0, 17 via knockouts.

"What the f**k happened? Like, what did I get hit with?," a battered and shattered Tszyu said in a brief post-fight press conference at the Caribe Royale resort in Orlando.

Boxing fans might be asking the same thing, having witnessed Tszyu knocked down fewer times in his entire 25-bout career before this brutal beat-down.

Tszyu had been bidding to join his Hall of Famer dad Kostya as only the second father-son in history to win at least two world titles each.

Instead Murtazaliev crashed the Tszyu family reunion in spectacular fashion and left Kostya consoling his battered and shattered son inside the ring after the merciless mugging.

Kostya was ringside for the first time since Tszyu's professional debut in Sydney eight years ago, while the vanquished star's mother must have thought she was also watching a horror show unfold from the front row.

"Things didn't go to plan. The better man won tonight, no excuses right there," Tszyu said.

"Yeah, no excuses. I tried my best and these things happen.

"Boxing's not meant to be perfect. So you live and you learn, right?"

Tszyu was also hoping - and expecting - to restore order seven months after relinquishing his WBO strap in a bloody, controversial split-decision loss to Sebastian Fundora in Las Vegas.

Now Tszyu will return to Australia with his future uncertain after enduring a second straight defeat, after opening his career with 24 wins.

"I couldn't regroup and I don't know, man, shit doesn't go your way and you just have to bounce back," he said of the devastating setback.

"I was positive after the Fundora (loss) but I've got to find more answers with this one.

"Like, this didn't go according to script. It was a little bit different."

An early head clash left Tszyu checking to see if the collision had reopened the ghastly cut that effectively cruelled his chances against Fundora.

Concussed, he later said he couldn't recall when asked if the head clash unnerved him.

But worse was to follow in the second round.

First Murtazaliev dropped him with a thunderous left hook, then he had Tszyu struggling to regain his senses after a heavy right-left combination.

A full-blown attack had Tszyu on the canvas for a third time and the fight appeared over.

It was when Murtazaliev delivered another left hook to finish Tszyu off with one minute, five seconds left in the third round.

"I'll be honest with you, I felt unbelievable," Tszyu said, trying to explain the defeat.

"I had a great prep.

"So he got me and he was the better man this night and we live and we learn."

The loss leaves the Sydney slayer's career in limbo.

He had been looking to move to the US in anticipation of mega-money fights with the likes of Fundora, Jermel Charlo, Errol Spence and pound-for-pound king Terence Crawford.

But where the soon-to-be 30-year-old goes from here now is anybody's guess.