Russia's Nikolay Valuev stopped American Monte Barrett in the 11th round to retain his World Boxing Association heavyweight crown.
The 33-year-old, who is listed at seven foot and 23 stone, knocked his much shorter rival down twice before Barrett's trainer stopped the fight.
The referee officially halted the bout two minutes, 12 seconds into the 11th.
Valuev defended the title he won from John Ruiz and took his unbeaten record to 45 wins with 33 knockouts.
"It was just a risky thing at that point, so I stopped the fight"
"The victory wasn't easy tonight and Monte Barrett tried really hard," said Valuev.
"I haven't fought in the US for a long time so this was a whole new thing for me. To be honest, I was a little nervous. I need to settle down more."
Barrett was magnanimous in defeat. "I couldn't get my range," he said.
"He's a very tough guy. I was trying to bring it to him. Much respect goes out to him."
Barrett's trainer Ali Bashir said he had no option but to stop the fight when he did.
"I thought Monte was in the fight that is why I let it go as far as it could go.
"I saw that he was tiring and he was hurt and there was no reason to go on. It was just a risky thing at that point, so I stopped the fight."
Barrett, who was also knocked down once in the eighth round, dropped to 31-5.
Valuev is one of four fighters from the former Soviet Union to hold the major belts, the others being Wladimir Klitschko, Oleg Maskaev and Serguei Lyakhovich.
The 35-year-old Barrett, who measures 6ft 3ins, lost on a unanimous decision last August to Hasim Rahman when they fought for the WBC interim title.
He was knocked out by Wladimir Klitschko in London in 2000, and won a split decision against ex-IBF and WBA champion Tim Witherspoon in 2001.
On the undercard, Poland's Tomasz Adamek successfully defended his WBC light heavyweight crown with a decision over Paul Briggs of Australia.
Adamek won on two of the three judges' scorecards while the third scored the fight even.