Muhammad Ali has died at the age of 74 after a 32-year battle with Parkinson's.
A statement from the legendary boxer's family confirmed his passing on Thursday evening at a hospital in Arizona, US.
The man dubbed 'The Greatest' had some unforgettable bouts in the ring and, here, Press Association Sport picks out five.
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Ali was well known for his flamboyant style. He would boast about being pretty and predict which round he would knock his opponent out.
The boxer, born in Kentucky, was involved in some of the best fights in heavyweight history.
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MUHAMMAD ALI v JOE FRAZIER III
Four years after their first meeting, Muhammad Ali and Joe Frazier faced off in the Philippines for the third and final part of arguably the greatest trilogy boxing has ever known.
Frazier had won their first fight in New York in 1971, shortly after Ali's return from suspension for avoiding the Vietnam draft, with Ali gaining revenge three years later prior to dethroning George Foreman in Zaire.
A third fight was inevitable, hastened as it was by an intense dislike between the two men which had festered throughout their two previous meetings, and which led Ali to make the jibe for which the title of the bout became known.
Ali boasted: "It will be a killa and a thrilla and a chilla, when I get that gorilla in Manila."
While Ali courted local dignitaries and the media in the build-up to the fight, just as he had in Zaire the previous year, Frazier preferred to stay in the shadows, propelled by the rage that Ali's remarks had lit within him.
By the night of the fight, Frazier was ready to go. He swarmed all over Ali, slamming home enormous left hooks and setting the pace for what would come to be regarded as one of the most brutal title bouts in boxing history.
The pace was unrelenting through 14 rounds, with both fighters dealing and sustaining tremendous punishment, before Frazier's trainer Eddie Futch decided to pull his man out before the start of the final round.
Unbeknown to Futch and Frazier at the time, Ali was also considering quitting, reportedly urging his corner to cut off his gloves, and later describing the bout as "the closest thing to death" he had ever known.
The win marked Ali's final truly great boxing performance, although he did manage to heroically rouse himself to win back the title he had lost to Leon Smith in September 1978.
MUHAMMAD ALI v GEORGE FOREMAN
Ali took part in some of the biggest fights in boxing history, but none proved more iconic than his mighty bout with Foreman in the dark heart of Africa: the legendary Rumble In The Jungle.
Ali's mission to win back the world heavyweight title seven years after being banned from boxing for refusing the Vietnam draft would have been a big story where ever it happened to be staged.
Thanks to the vision of an audacious new promoter called Don King, it was set for Kinshasa in what was then known as Zaire, whose despotic president Mobutu Sese Seko stumped up the cash in a bid for international recognition.
Ali had returned from suspension and slowly built himself back into title contention, his decision win over Frazier in January 1974 finally earning him a shot at reigning champion Foreman.
Like Sonny Liston before him, Foreman was a surly, big-punching favourite who had battered Frazier in two rounds to take his titles the previous year, and was seen to have too much heavy weaponry for a rusty Ali to repel.
During the fight build-up, Ali courted the world's media and earned the adoration of the Zairean people, in contrast to Foreman, whom it appeared wished he was anywhere else but Kinshasa.
Even an enforced one-month delay due to a cut eye did nothing to quench Ali's enthusiasm, and by the time the pair stepped in the ring in October 1974 he had made even his harshest critics believe another miracle may just be possible.
Expected to try to dance away from Foreman's big shots as he had against the likes of Liston and Cleveland Williams before him, Ali did precisely the opposite.
For round after round, Ali covered up in the ropes - a tactic soon to be immortalised as 'Rope-a-dope' - allowing Foreman to pummel away, gradually using up his reserves of energy in the process.
Ali would taunt Foreman and flick out fast jabs which noticeably puffed up Foreman's face. Foreman's angry responses only served to sap him more. By round eight, the fight began to take an extraordinary shift in momentum.
Midway through the eighth, Ali pounced, landing a pair of right hooks followed by a combination of shots that sent Foreman spiralling to the canvas, where he failed to beat the count.
Ali would go on to have more brutal fights and retain his title until 1978, when he was shocked by a young Leon Spinks. Foreman would not win back the title until 16 years later when, astonishingly, at the age of 45, he knocked out Michael Moorer.
But for all their epics before or since, nothing quite came close to matching the story of the Rumble In The Jungle, when the whole world watched transfixed as the most captivating chapter in Ali's astonishing career unfolded before them.
CASSIUS CLAY v SONNY LISTON
When Cassius Clay, Ali's previous guise, prepared to challenge Liston for the world heavyweight title in Miami in February 1964, he was considered little more than an audacious no-hoper.
Clay's status as a rising star had suffered somewhat in his previous fight, when he had been knocked down and on the verge of defeat against the game but limited Henry Cooper in London.
Yet the 22-year-old was prepared to risk it all against the ogreish champion Liston, who by complete contrast was coming off the back of two consecutive first-round victories over Floyd Patterson.
Only three of the 46 ringside reporters for the fight tipped Clay to win. Most had considered Clay's extraordinary antics in the build-up to the fight to be borne out of sheer terror rather than any display of confidence.
Liston, a former convict who learned to box while serving time for armed robbery, was used to beating his opponents by the time they stood face to face on the weighing scales.
Yet here was the brash Ali taunting Liston at every turn, deriding him as a 'Big Ugly Bear', donning camouflaged attire and driving a bus to gatecrash Liston's training camp.
Clay's antics on the day before the fight prompted one physician to claim that Clay was "literally, almost scared to death."
But it became clear from the early moments of the fight that Clay's boasts were far from misplaced. He used his superior speed to stay out of range of Liston's punches and make the champion look slow and awkward.
Through the early rounds, Liston pawed fruitlessly after Clay, who responded by clattering home punches from either hand which served to slowly drain the fight from a man who was used to having things all his own way.
At the end of the fourth round, Clay returned to his corner claiming to be blinded by a substance on Liston's gloves - he was ready to pull out, but his vision slowly returned through round five, and by the sixth he was back to his best.
After his most dominant round yet, Clay noticed Liston spit out his gum shield and quit on his stool.
Clay jumped to his feet, jabbing his glove at the sports writers at ringside and demanding that they 'eat their words'. He also first roared the sentiment which would follow him through the rest of his career and for the rest of his life: "I am the greatest!"
Fifteen months later, the pair met again, Liston folding in the first round from a so-called 'phantom punch' which inspired conspiracy theories about mafia involvement that continue to this day.
Liston fought on at a lower level, his last fight coming with a retirement win over Chuck Wepner in June 1970. Six months later, he died in mysterious circumstances in his home in Las Vegas.
MUHAMMAD ALI v LEON SPINKS II
Just when it seemed Ali's brutal win over Frazier in October 1975 had taken most of of the fight out of him, he returned to record a triumph which deserves to rank alongside his very best.
At the age of 36, no longer quite so fleet of foot and teetering in terms of punch resistance, Ali somehow willed himself to rise once more and become the first man in history to win the world heavyweight title three times.
In the aftermath of his fight with Frazier, few had denied Ali the right to undertake an easy world tour, recording wins over the likes of Jean-Pierre Coopman and Richard Dunne, gutsy men who were hardly fit to hold his punchbag.
In September 1976 things got serious again, as Ali barely scraped an unpopular unanimous decision over Ken Norton, then did the same against Alfredo Evangelista and the fierce-punching Earnie Shavers.
Ali's performance against Shavers prompted some in his team to insist he retire, but instead Ali pressed ahead with a match against the brash and cocksure 1976 Olympic champion, Spinks.
Spinks had made his professional debut in January 1977, and got into the ring with Ali in Las Vegas just over a year later having had just seven paid bouts. It was supposed to be a mismatch, even for a clearly ailing Ali.
However, Spinks embarrassed Ali, using his speed and youth to out-hustle the champion and rip away his title via a split decision.
Just when it seemed there was nowhere else for a despondent Ali to go, there was time for one more wonder. Spinks granted an immediate rematch, which would take place in New Orleans just seven months later.
Spinks started favourite, but his months of non-stop partying since he won the title started to show. Ali, by contrast, had worked himself back into shape and proceeded to easily out-work Spinks to win the title back once more.
It was a performance that could boast neither the sheer brutality of the Thrilla in Manila, the bouncing genius of his knockout of Cleveland Williams, nor the tactical acumen of the Rumble In The Jungle.
But in the context of his long career and seemingly inexorable decline, Ali's ability to rise one more time and defeat a fighter who, for all his faults, was a young up-and-comer who had beaten him clearly just seven months earlier was a remarkable feat.
It was one that should have brought a triumphant end to Ali's boxing career. Instead, sadly, he fought on, stopped by Larry Holmes in October 1980, and also defeated in an appalling bout with Trevor Berbick in the Bahamas the following year.
Spinks kept fighting until 1995. In retirement he fell on heard times, and now works at a McDonald's restaurant in Nebraska. His son Cory Spinks won the world light-middleweight title in 2003.
MUHAMMAD ALI v CLEVELAND WILLIAMS
He may have had other fights that earned more column inches, provoked more dramatic promotional campaigns, awakened more conspiracy theories, or just generally thudded louder through generations to follow.
But many maintain the true boxing greatness of Ali was never better exemplified than the night in November 1966 when he took on the ageing but ferociously hard-hitting Williams at the Houston Astrodome.
The crowd - an indoor record of 35,460 - sensed an upset, and Williams certainly came equipped. A big puncher, he had made his name in two brutal bouts against Liston in 1960, both of which he lost.
Despite having been inactive in 1965 due to being shot by a policeman over a traffic violation, he pronounced himself ready to face Ali. His manager Hugh Benbow said: "Cleve don't fool around. He's knocked 50 guys deader than cow meat."
Williams' plan was to stalk Ali and hope to land one of his big shots. Cooper had already proved what could happen if he landed flush. Unlike Liston, Williams seemed completely unfazed by the prospect of facing Ali.
But Ali knew Williams would have to catch him first. Right from the first bell, at which he had been lustily booed, Ali bounced on the balls of his feet and proceeded to dart out of Williams' reach.
Evading his opponent's increasingly frustrated swings, Ali flicked in with scoring punches off the back-foot, pumping home his left jab with unerring accuracy while Williams barely managed to land a punch in the hour.
In the second round Ali stepped up a gear, flooring Williams three times in quick succession towards the end of the round with stunning counter-shots which once again went unchallenged.
Ali's respect for Williams was obvious. He knew the longer the bout went on the more chance he stood of getting caught. In his next fight, Ali would deliberately extend Ernie Terrell the full 15 rounds to make him pay for a perceived slight. Not so Williams.
Only Williams' tenacious fighting spirit forced him to return upright for more punishment. The bell delayed the inevitable, but early in the third round, Ali knocked Williams flat on his back once more, and the referee waved the contest off.
It was a near-perfect performance from Ali, who gained back some public support as a result, although he would only fight twice more until his refusal to enter the US draft saw him stripped of his title and banned from boxing for three years.
Although he rebounded with three successive first-round wins, his loss to Ali signalled the end of Williams' top-level career. He eventually retired in 1972, and died in a traffic accident in 1999 at the age of 66.