George Kambosos Jr has declared he's "not finished yet" despite being stopped for the first time in his career in the IBF lightweight world title showdown against Vasiliy Lomachenko in Perth.
Lomachenko controlled Sunday's bout from start to finish in his technical knock-out victory in front of 14,147 fans at RAC Arena.
The fight was brought to a halt with 21 seconds remaining in the 11th round after Kambosos suffered a battering in the corner.
Kambosos had hit the deck seconds earlier following a powerful hook to the body.
When the referee resumed the bout, Lomachenko finished the job with a flurry of punches.
Jim Kambosos, the father of George Kambosos, revealed he was about to throw in the towel just as the referee stepped in to stop the bout.
When the fight was stopped, Lomachenko was winning on the judges' cards 99-91, 99-91, 98-92.
"I'm a blood and guts warrior. You know I leave it all in the line," Kambosos said after the defeat.
"I didn't want to get stopped. I wanted to get back up but the ref and obviously my father always look after the fighter.
"I've got a family, I've got three kids and and I've got to go back to them and show them that Dad's still here, Dad's still healthy. Kambosos is a good talker, so we don't want to be slurring our words."
Kambosos shot to international fame in 2021 when he won the IBF, WBA and WBO lightweight belts by stunning Teofimo Lopez at Madison Square Garden.
But back-to-back losses to Devin Haney - combined with last year's unconvincing and controversial win over Maxi Hughes - meant Sunday's fight against Lomachenko was make-or-break.
Kambosos will take a break before deciding what's next in his career.
But he made one thing clear: "It's not finished yet."
"Lomachenko, what can I say? He's a true champion, a legend of this sport," Kambosos said.
"This guy is one of the best of all time.
"We tried our best, but he's a good champion. He deserves that belt. I gave it my all.
"I'm still alive, I'm still standing. I ain't dead."
Lomachenko (18-3, 12KOs) became the first person to stop Kambosos (21-3, 10KOs).
"It was not a goal of mine," Lomachenko said of the TKO victory.
"I expected more. Style makes fights, and today my style was better."
There was plenty of theatre in the lead-up to the fight, with the pair engaging in a three-minute staredown on Thursday, and a lengthy reprise at Saturday's weigh-in.
After a cagey start to the bout, Lomachenko landed a few crucial head blows after trapping Kambosos in the corner.
The fourth round was particularly brutal for Kambosos as he wore a series of powerful jabs and left hooks from Lomachenko.
Kambosos momentarily rattled Lomachenko in the sixth with a strong jab, but it was a fleeting moment in a bout the Ukrainian was controlling.
Lomachenko's powerful left hook left Kambosos with blood streaming from near his right eye in the eighth round, and as the onslaught continued the Australian was left a bloodied mess by the end of the ninth.
Whether Kambosos could see out the fight was the main question from that point on, and Lomachenko gave an emphatic answer in a brutal 11th round.
