Floyd Mayweather stopped Conor McGregor on his feet, against the ropes, in the 10th round of their Las Vegas extravaganza.
Mayweather extended his record-breaking career to 50-0 at the expense of the debuting UFC superstar who was tough, but ultimately out-skilled.
The American registered his first stoppage since toppling Victor Ortiz in 2011 as he surpassed the 1950s heavyweight Rocky Marciano to further establish himself as an all-time boxing great.
McGregor had started the fight impressively but faded and, being forced backwards for two rounds, was eventually pummelled by a barrage of unanswered shots forcing referee Robert Byrd to intervene.
"I would have liked the ref to let me keep going," McGregor said afterwards. "I was a little fatigued, early on I thought it was handy, I have to give it to him."
The first significant punch was a slick uppercut by McGregor that answered questions about his skills and Mayweather's chin despite his two-year retirement. His hubris was quickly evident, as he put his hands behind his back to goad his more experienced rival.
McGregor certainly looked the part in the opening rounds, definitely winning his fair share, although his feet and reflexes dipped in the fourth and fifth. As five-division world champion Mayweather began finding a home for his right hand, he ended the fifth round by spitefully shoving McGregor back to his corner.
McGregor's holding was being punished more and more frequently and he spent periods of the sixth round going backwards as Mayweather's fast hands flashed past his guard.
The Irishman's tiring feet were beginning to catch him in a defenceless position and Mayweather, taking advantage, snapped his head back with straight punches. McGregor took a noticeably huge inhale of breath after the seventh.
Free from the defensive shell in which he started the fight, Mayweather began aggressively walking McGregor in the eighth and bloodied his face when the debutant all too frequently couldn't find a sideways exit.
McGregor's arms were lethargically low and his three-and-a-half pound weigh-in advantage (estimated at 15lbs during the fight) hindered him when the more nimble Mayweather went on the hunt. In the ninth, he sensed a stoppage which was only kept at bay by McGregor's ruggedness.
And McGregor's toughness never failed him, even at his demise. He was sent stumbling backwards by a Mayweather right hand but never went down - several more blows to the face caused the conclusion.