On October 30, 1974, Muhammad Ali knocked out George Foreman in the eighth round of a 15-round bout in what was then known as Kinshasa, Zaire (now the Democratic Republic of Congo).
Foreman was the favourite, a champion both bigger and younger than his opponent. But Ali used all of his boxing know-how to engineer a victory.
Using what he later called 'rope-a-dope' tactics, Ali stood against the ropes and soaked up all that Foreman could throw at him before knocking out his opponent, who rapidly wilted in the Kinshasa heat.
It's been dubbed one of the biggest upsets in sporting history.
Ali's fame and style went far beyond the ring, showing a flair in front of the cameras during his colourful press conferences.
"I said last night, I had a dream, when I got to Africa I had one hell of a rumble, I had to beat Tarzan's behind first for claiming to be the king of the jungle, for this fight I wrestled with the alligators, I've tussled with a whale, I done handcuffed lightning and put thunder in jail," he told reporters in the lead-up to the fight.
"I have murdered a rock, I injured a stone and I hospitalised a brick, I'm so bad I make medicine sick, I'm so fast, man, I can run through a hurricane and don't get wet, when George Foreman meets me he'll pay his debt, I can drown a drink of water and kill a dead tree, wait 'til you see Muhammad Ali."
Long before his dazzling footwork and punching prowess made him a three-time world heavyweight boxing champion, Ali (born Cassius Marcellus Clay Jr.) honed his skills by sparring with neighbourhood friends and running alongside the bus on the way to school.
Ali began his boxing career as an amateur in Louisville in the 1950s, won a gold medal in boxing in 1960 at the Olympics in Rome.
He went on to become a three-time world heavyweight champion, first winning the title by defeating Sonny Liston in 1964.
He converted to Islam soon after his win and changed his name to Muhammad Ali.
However, in 1967 Ali had his boxing licence suspended and was stripped of his WBC and WBA titles.
Labelling himself a conscientious objector, Ali refused induction into the military service - with the US Army at that time engaged in war against North Vietnam - refusing to fight in the war because of his religious beliefs.
Ali received a five-year prison term for draft evasion, but remained free while his case was on appeal.
The conviction was eventually quashed by the Supreme Court in 1971.
His return to the ring came in March of that year, when he faced Joe Frazier, who held the WBC and WBA heavyweight titles that formerly belonged to Ali.
Frazier retained his belts following a unanimous decision from the judges at the end of 'The Fight of the Century'.
Ali won his rematch against Frazier, who had lost his titles to George Foreman at the start of 1973.
But Foreman would lose the titles to Ali in "The Rumble in the Jungle".
A rematch in the Philippines with Frazier - the 'Thrilla in Manilla' - followed in 1975.
Ali won by Technical Knockout (TKO) in the 14th round, but any retirement plans were soon put on hold.
He made six more successful defences of his WBC and WBA titles before he lost a split decision to Leon Spinks in 1978, only to reclaim the belts with a unanimous decision in the rematch that same year, after which he announced his retirement from boxing.
After a two-year sabbatical, Ali returned to the ring in 1980, but he suffered a tenth-round TKO to Larry Holmes and lost to a Trevor Berbick a year later by way of a unanimous decision.
That proved to be the final fight of Ali's career, which he finished with a record of 61 bouts, 56 wins (37 by knockout) and five losses.
Shortly after retiring from the ring, Ali was diagnosed with Parkinson's Disease - a degenerative disorder that effects the central nervous system.
