The most iconic photo in boxing history documents the knockout that almost nobody saw happen.

Even before the first punch was thrown, the May 25, 1965 bout between Muhammad Ali and Sonny Liston, during which the photo was snapped, was already shaping up to be the stuff of legends.

Ali first fought Liston in 1964 as Cassius Clay

The match had more storylines than a soap opera. Boxing’s brightest young star was again squaring off against a renowned bruiser in a rematch of their thrilling and controversial heavyweight championship fight one year prior, a fight that was followed by 14 months of international intrigue and the combustible politics of the 1960s.

In the first fight, in Miami, a 22-year-old Cassius Clay danced around the ring, taunted Liston, promised reporters he’d shock the world, and then delivered on that promise with a blistering late attack that prompted Liston to toss in the towel after the sixth round. It made a champion out of Clay, who declared that he’d “shook up the world.”

That would prove to be an understatement. According to a report in the Miami Herald a few weeks before the 1964 fight, Clay was consorting with members of the Nation of Islam, who Clay’s father claimed had “brainwashed” his son. Clay brought Malcolm X along with him to Miami, and amid the controversy, the fight was almost canceled. He offered no comment on the matter, but his victory would soon turn it into an international story.

Suddenly, the world had to come to grips with a new kind of heavyweight champion. According to a New York Times report the day after the fight, Clay was indeed an official member of the Nation of Islam. The organization was seen as an extremist anti-white people hate group and opponents of desegregation and Martin Luther King Jr. Clay’s propensity for self-promotion and controversy seemed to fit in with the group’s inflammatory rhetoric.

The rumors swirling nearly canceled the fight the night prior, and when a reporter that morning broke tradition and asked if Clay was a member of the “Black Muslims,” as the group was often called, the boxer confirmed his new religion. He used the platform to expound on the political theory that was so reviled in white America, defending Malcolm X and condemning racial oppression — this was still months before President Lyndon B. Johnson signed the Civil Rights Act of 1964.

“I don’t have to be what you want me to be,” Clay told agitated reporters. “I’m free to be who I want.”

Soon, he was known as Cassius X, eschewing the last name given to his enslaved family by their owners. Less than 10 days later, he was Muhammad Ali, a name given him to Elijah Muhammad, the head of the Nation of Islam.

Liston was controversial in his own right

There were plenty of tough questions after the first fight for Liston, too, namely, why didn’t he come out for another round? Due to Liston’s long association with the mafia and the reputation as a peerless tough guy, there was speculation that he’d thrown the fight for some financial reward.

The FBI was on the hunt for evidence for match-fixing, given Liston’s mob ties — mobsters still owned much of his fight promotion contract — and the sport’s shady business model. But a Senate subcommittee hearing turned up no evidence of any match-fixing, and doctors confirmed his explanation that he’d taken such damage to his shoulder that he couldn’t feel his arm.

It was more likely that Liston was out of shape — according to a story in Esquire at the time, Liston “trained as normal, running around five miles a day, eating hot dogs and drinking beer.” He was also possibly much older than his listed 32 years than anything else — Liston was the second-youngest of 25 children to parents who didn’t exactly keep records of birthdates.

The rematch almost didn’t happen, either

Technically, contracts for boxing matches weren’t supposed to have rematch clauses, though pretty much all of them had some sort of loophole and agreement when each side wanted to guarantee a return bout — again, the laws by which boxing governed itself were really more suggestions at the time. In this case, Intercontinental Promotions Inc., which had the rights to Liston’s fight, also got to choose the first opponent for the new champion, should Liston lose. Naturally, they decided that Ali would take on Liston.

The World Boxing Association — one of several boxing organizations — was not too pleased, moving to strip Ali of his title and advising states not to agree to host the rematch. Only Massachusetts was willing to host the fight, though it was delayed from November 1964 to May 1965 so that Ali could recover from hernia surgery.

During the interim, officials in Boston also got cold feet. Liston kept running into trouble with the law and Ali had a target on his back after the assassination of Malcolm X, whom he had disavowed after Elijah Muhammad forced him out of the Nation of Islam. Suffolk County, where Boston is located, ultimately pulled the plug, leaving them without a venue with less than a month to go. The governor of nearby Maine, John Reed, stepped up and volunteered to host it in the small town of Lewiston, where a resort and ice rink could provide some infrastructure.

Ali brought his big personality to the small town, but Liston was still the favorite. He’d shown up to the fight in the best shape of his life — no hot dogs or beer in his diet this time — and promised to take down Ali.

Muhammad Ali stands over Sonny Liston after dropping Liston with a short hard right to the jaw on May 25, 1965, in Lewiston, Maine

Muhammad Ali stands over Sonny Liston after dropping Liston with a short hard right to the jaw on May 25, 1965, in Lewiston, Maine

The fight and 'phantom punch' shook the world

People around the world tuned in via satellite to watch the match, which was fought in front of 2,434 paying ticket-holders, the smallest crowd in heavyweight championship fight history; people there suggested the crowd was more like 4,000, but nonetheless, it was a very small in-person audience. And it was probably for the best — ticket-buyers didn’t exactly get their money’s worth.

The fight lasted less than one full round, with Ali knocking out Liston at the 1:44 mark. It was a shocking result, not only because Liston was favored in the match, but because hardly anybody saw the punch that took him down. Liston had thrown a jab with his left arm and, leaning forward, took a right hook from Ali right to the skull. He sunk to the canvas, and as he was down, Ali stood over him, taunting and demanding his stunned opponent get back up. The photo captures the champion’s exhortations, with all the fire and passion and dynamic physicality that made him such a phenomenon.

Liston did eventually rise from the mat, but soon after, the referee broke up the two boxers once again — the former champion had been down for more than 10 seconds, ending the fight.

Audiences at home were confused and outraged. Liston had never been knocked out before, and most people didn’t even see the punch happen. It became known as the “phantom punch” and has been the subject of controversy and speculation for the last 55 years. Entire books have been written about the fight, and one, released in 2015, sought to end the suggestion that Liston took another fall.

“Any objective observer would have had to concede that Ali's counterpunch had landed, and landed with enough force to turn Liston's head,” Rob Sneddon wrote in The Phantom Punch: The Story Behind Boxing's Most Controversial Bout. Rocky Marciano, the former heavyweight champion, said that he appreciated the punch’s strength upon re-examination. “I didn't think it was a powerful punch when I saw the fight from ringside," he said. "Now (after seeing video) I think Clay, seeing the opening, snapped the punch the last six inches.

For his part, Liston said that the referee’s inability to keep track of time doomed him, as he didn’t know when to get up from the mat. He allegedly later told an assistant that he took a dive because he was afraid of the consequences of beating Ali — he thought it would put a target on his own back.

Ali would lose his title a year later, though it didn’t happen in the ring. The champion was stripped of the belt when he refused to be drafted into the armed services during the Vietnam War, and he didn’t box again in a match that counted until 1970. A few months after Ali’s fight, Liston was dead from lung congestion — though even that was shrouded in mystery and controversy.