Australian super welterweight Tim Tszyu has lost his rematch against Sebastian Fundora, failing to come out for the eighth round at the MGM Grand in Las Vegas.
Tszyu was dropped in the first round and cut in the second in a nightmare start.
The giant American, with a reach advantage of 24cm and a height advantage of 23cm, was dominating Tszyu in the opening exchanges.
After that though, Tszyu looked to be getting back into the contest.
The Australian landed significant blows with his overhand right, gauging the distance superbly and once again bloodying Fundora's nose, just as he did in their bloody first encounter.
However, just after an impressive seventh round, Tszyu stunned the crowd by failing to answer the bell to start the eighth round, remaining on his stool when asked whether he wanted to continue.
"I tried to give it everything and I just couldn't do it," Tszyu said in the ring post-fight.
"The victory belongs to Sebastian Fundora, the best man at 154 pounds.
"He was just the better man."
The Tszyu camp told Main Event post-fight that it was their decision to withdraw their fighter and not Tszyu withdrawing himself.
The defeat raises significant questions over Tszyu's future at world level though, following a third devastating defeat in his last four fights — all three in America.
Later, eight-weight world champion Manny Pacquiao returned to the ring aged 46, and gave WBC welterweight champion Mario Barrios an enormous scare by battling to a majority decision draw.
Barrios was awarded the decision by one ringside judge 115-113, while the two others could not split the fighters with a 114-114 verdict.
"I thought I won the fight," Pacquiao, who has not tasted victory in the ring since 2019.
"It was a close fight, but I thought I did enough."
Pacquiao was superb, belying his age with an energetic display with flashing hands and tremendous endurance.
Barrios was unable to impose himself on the Filipino fighter, but kept him at range with some accurate jabs and did just enough to retain his title.
Look back on how all the action unfolded in our live blog.
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