In a fight of razor-thin margins, Crawford poured it on in the closing rounds to earn a unanimous decision victory, improving his unblemished record to 42-0 with 31 knockouts.

Crawford, 37, had jumped up two weight categories to vie for history, having already counted undisputed titles at super lightweight and welterweight among his titles in four -- now five -- weight classes.

He silenced critics who claimed his sparkling resume was packed with substandard opponents and quieted a raucously pro-Alvarez crowd of 70,482 at Allegiant Stadium, home of the NFL's Las Vegas Raiders.

"For sure this is definitely a signature win," Crawford said. "Moving up two weight classes, being the B-side, fighting a guy that's been undefeated in the division, undisputed.

"My other undisputed runs I had titles, I was coming in as a champion as well. But this one I was coming in as an underdog, no championship belts and I felt like everything was on the line."

One judge scored it 116-112 for Crawford and the other two saw it 115-113 for the American, who had nothing but praise for his opponent.

"Canelo is a great champion," Crawford said. "And he fought like a champion today."

But Crawford added: "I think I was the better man today. I was stronger, I punched harder.

"It means a lot to me," Crawford said. "You know anybody can be a nobody, and that's all they say I've been fighting is nobodies.

"So what can they say now?"

Alvarez, 35 and a world champion in four divisions, fell to 63-3-2.

Crawford frustrated Alvarez with his agility and speed, losing none of his quickness as he stepped up to the 168-pound (76.2-kg) category.

He weighed in at the same 167.5 pounds as Alvarez, a career high for Crawford, who had never fought above 147 pounds until last year when he weighed 153.5 in a unanimous decision victory over Israil Madrimov.

Alvarez, boxing's biggest star for the past decade, simply couldn't get at him, and Crawford used his jab and landed combinations with a vengeance in the closing rounds after wearing the champion down.

Crawford raised his arms and then sank to his knees when the final bell rang, having earned grudging admiration even from the hostile crowd.

- 'Defeat doesn't define me' -

Alvarez, who will reportedly make $100 million for the fight, had won six straight fights since a loss to Dmitri Bivol in May 2022.

"A defeat does not define me," he insisted as he opened the door to a rematch.

"If we do it again, it will be great," Alvarez said.

There was little to separate the two through the first six rounds.

Alvarez went to the body early in a bid to slow the challenger down.

The action was picking up in the fourth, Crawford landing more combinations and proving a slippery target.

Crawford's hand speed was making difference in the sixth, and in the seventh he was making use of his longer reach and outworking the champion, who came off worse in most exchanges.

Both fighters came out firing in the ninth, Crawford punishing Alvarez with a string of combinations.

The American was shaken by an accidental headbutt that caused a cut, but he continued to pour it on and Alvarez could find no answer.

"I did what I was supposed to do, I tried every way very hard," Alvarez said. "I tried my best but I didn't figure it out.

"I hit Crawford, but not clean shots with all my power. He's a good fighter, knows how to move."

The bout was promoted by Saudi Arabia's Riyadh Season, which inked Alvarez to a four-fight deal that made him the latest in a growing list of boxers to flock to the kingdom for mega paydays.

Riyadh Season teamed with UFC mastermind Dana White to promote the fight that was streamed globally by Netflix.

Former heavyweight world champion Mike Tyson and Mexican ring icon Julio Cesar Chavez were among a raft of current and former fighters among the celebrities in attendance.

Oscar-winner Charlize Theron was among a Hollywood contingent that also included actors Mark Wahlberg and Jason Statham, Grammy-winning musician Kendrick Lamar, Chance the Rapper and YouTuber MrBeast.