Conor McGregor stopped Jose Aldo with one spectacular punch just 13 seconds into the first round, backing up his bravado and claiming the undisputed featherweight title at UFC 194.
McGregor (19-2) finished the fight in Las Vegas with an electrifying exchange shortly after the opening bell, slipping Aldo's lead right and cracking Aldo on the jaw with a huge left hand.
Aldo (25-2) actually finished his punch and hit McGregor with a left, but the champ fell senseless to the ground and McGregor pounced, only to be pulled off in victory.
Aldo had won 18 consecutive fights over the last 10 years, but nothing seems to slow McGregor.
The loquacious Irish brawler goaded Aldo throughout the promotion of their delayed bout, only to back up every word he said.
"He is already beaten," McGregor said prior to the fight. "I look in his eyes, and I see someone who knows his era is over. It's a new era. It's my era. I almost want to comfort him. I want to say, 'Don't worry. It will all be over soon.'"
Aldo was the only featherweight champion in UFC's short history. The Brazilian was widely considered the pound-for-pound best mixed martial artist in the world. He had not lost a fight in 10 years.
'Green Christmas in Las Vegas'
Aldo and McGregor traded innumerable insults and menacing glares during the build-up to this injury-delayed showdown.
"I get in there, and I put on a show," McGregor said. "I come to fight, and this fight will be a performance. I'm not just going to beat Jose. I'm going to embarrass Jose in there. I don't need to gather any more intel, any more research. It's done. He has already lost."
"I feel the Brazilians will come out to support. They're going to be swallowed by the Irish, though. It's going to be a green Christmas in Las Vegas, that's for sure."
Aldo could say little when he was injured in training shortly before he was originally scheduled to meet McGregor in July, scrapping an elaborate promotional campaign and providing more fodder for his challenger.
McGregor took on the highly regarded Chad Mendes instead, scoring a second-round stoppage and earning an interim belt.
That honour didn't satisfy McGregor, whose plans for world domination aren't confined to one weight class or even one endeavour ("Hollywood is screaming for me," he said).
McGregor has attracted global attention to the grateful UFC, which has heavily showcased his magnetism and verbosity.
He has become a fan favourite - particularly among his countrymen, who filled Vegas' casinos with songs and revelry before and after his victory over Mendes.