Clay had been studying the doctrines of the Nation of Islam, more popularly (and disparagingly) known at the time as the Black Muslims. He responded to the organization's declaration that American blacks needn't seek assent for civil rights – rather they should be proud of their racial identity and govern their own ends. The public face of the movement was Malcolm X, who since 1954 had served as chief minister at the Nation's Harlem mosque and as a right-hand man to the organization's leader, the soft-voiced but steel-minded Elijah Muhammad. Malcolm spurned the goals of American civil rights campaigners as too conciliatory. In the last year of his life, he famously said, "We declare our right on this Earth to be a man, to be a human being, to be respected as a human being, to be given the rights of a human being in this society, on this Earth, in this day, which we intend to bring into existence by any means necessary." Many politicians, journalists, law-enforcement members, and even other black leaders regarded Malcolm X as the most dangerous voice in America. That voice, though, had an appeal for a young man who used to lie awake at night fearing the nightmare fate that had befallen Emmett Till.
Malcolm hadn't heard of Cassius Clay when they first met in 1962. The Nation viewed boxing as a practice that exploited young black men. But he was taken by Clay's authentic enthusiasm and saw in him a popular figure who might advance the Nation of Islam's appeal for other young black Americans. It was Malcolm X, more than anybody, who addressed Clay's uncertainty. "This fight is the truth," Malcolm told him in Miami before the match. "It's the Cross and the Crescent fighting in a prize ring – for the first time.... Do you think Allah has brought about all this intending for you to leave the ring as anything but the champion?" Clay had tried to keep his new alliance secret, but in early February, Cassius Clay Sr. told a Miami Herald reporter that "Cassius had become a Muslim; that they'd brainwashed him to hate white people, and as soon as the fight was over, he was going to change his name." Under pressure from the fight's promoters – who threatened to cancel the bout – Malcolm X left Miami, though he returned the day of the match and sat ringside with R&B singer Sam Cooke and his manager, Allen Klein.
Clay had started to signify something unsettling, even threatening, in the American moment. As a result Sonny Liston found himself, for the first time, with a mandate from boxing pundits: to put the loudmouth upstart in his place. It wouldn't be a pretty business. The champion had a crushing left punch: "It's gonna go so far down [Clay's] throat," said Liston, "it'll take a week for me to pull it out again." Malcolm X, though, had rekindled Clay's faith in himself. The morning of the match, Cassius crashed into the weigh-in ceremony, yelling, "You ain't got a chance.... You whupped!" One reporter said the fight should be called off, that Clay was hysterical and was endangering himself.
Cassius Clay was 22 the night of his first fight with Sonny Liston. The New Jersey Star-Ledger's Jerry Izenberg, listening to the radio on his way to Miami's Convention Hall, heard: "[Clay] has been seen at the airport, and he's bought a ticket to go to South America." He heard another report that Florida's governor wanted the fight called off "because he doesn't want blood on his hands." Seated later in the ringside press section, Izenberg heard similar speculation, and then looked over his shoulder and spotted Clay. "There he is," he said, "standing in the aisle, wearing his shirt, trousers, hasn't changed. He's as cool as a cucumber. And I say to myself, 'Hey, we have all gone for something here.' But he still can't win this fight." New York Times reporter Robert Lipsyte, also in the press section, had been instructed by his newspaper to map the shortest route to the hospital. "I understood perfectly," he said, "that I'd never see Cassius Clay again."
When the fighters met at ring center, though, perceptions changed. "This is the first time we had really seen them," said Lipsyte. "There was a collective gasp: Cassius Clay was much bigger." Once the bell rang, the challenger moved immediately into his opponent, hitting with blindingly fast and precise jabs, and he circled constantly – making himself a shifting target. Liston threw hard but desperate swings, sometimes off-target by a foot or more; Clay's recoil reflexes were better than fight fans had witnessed before. Plus, though it had often been noted that Ali's spry and strong legs were his best tool in the ring, he had tremendous strength, using his shoulders to push the full reach and momentum of his fists. Near the round's end, Clay let loose with a volley of punches that landed from unpredictable angles. Liston was stunned. Commenting after the round at ringside, former champion Joe Louis said, "I think this is one of the greatest rounds of any fight we've seen in a long time.... Clay completely outclassed Sonny Liston in this round."
In the second round, Clay caught Liston with a sharp uppercut to the right cheekbone, drawing blood. "Starting in the third round," Ali later said, "I saw his expression, how shook he was that we were still out there, and he was the one cut and bleeding.... I saw his face up close when he wiped his glove at that cut and saw the blood." Between the third and fourth rounds, Liston reportedly took a dishonorable course. In King of the World, author and New Yorker editor David Remnick relates the tale that Liston instructed one of his cornermen to "juice his gloves" – that is, apply a strong liniment or coagulant that, if it made contact with the eyes, would burn and temporarily blind. It worked: Clay left the fourth round blinking wildly, his eyes hurting intensely. He wanted to stop the fight – "He was telling us to cut the gloves off," said Ferdie Pacheco. Angelo Dundee had to hold him back from complaining to the referee about Liston's dirty fighting. He knew that if the bout was stopped, it might be impossible for Clay to get another chance at the title. The trainer instead washed out the young challenger's eyes and stood him up for the next round. At that crucial moment of Muhammad Ali's career, Dundee pushed him forward, saying: "Big daddy, get in there; this is your night."
In the fifth round, Liston caught Clay and pounded his torso savagely – "snorting like a horse," said Ali – but the challenger could absorb the worst of it. In the sixth, Clay worsened the cut he'd opened earlier under Liston's eye. "Sonny's face was a mess," reporter Robert Lipsyte said, "and he couldn't do a thing to stop this terrible thing that was happening to him." At the round's end, a disheartened Liston told his trainers, "That's it," and spat out his mouthpiece. The fight was over: Cassius Clay was the new world heavyweight champion. He pushed through the crowd that swarmed him to the ringside where reporters sat, looking shocked. "Eat your words," he told them. "I told you and you and you. I'm king of the world. You must all bow to me!" Moments later he asserted: "I shook up the world!" The press hated him for it. Two days after the event, the New York Herald Tribune wrote that Clay was "shrilling to the world in tones that seemed to echo a thousand little Hitlers through all the ages of man."