Four years before Muhammad Ali won his first world title bout, the 18-year-old, then known by his birth name of Cassius Clay, travleled to Rome to compete in the 1960 Olympics.

Clay had proven himself to be a talented amateur, winning six Kentucky Golden Gloves championships, back-to-back National Amateur Athletic Union titles and 100 out of his 108 fights.

The American had to overcome a fear of flying in order to travel to Italy for the Games, and considered withdrawing from the USA team when he was told he could not go by train or ship, before deciding to fly while wearing a parachute.

Once in the ring, the teenager soon established himself as a contender for the title, stopping first-round opponent Yvon Becaus in the second round of their match, before eliminating 1956 middleweight Olympic champion Gennediy Shatkov.

Clay faced a sterner test in the semi-finals, coming up against Australia's Tony Madigan. However, the future world champion was awarded a unanimous points decision by the judges.

Poland's Zbigniew Pietrzykowski awaited the 18-year-old in the gold-medal fight. Clay struggled in the first round against the southpaw, having to absorb a number of punches from his opponent.

Clay had his guard up in the second round to avoid taking further punishment, but had enough left in the tank for a big finish, connecting with a series of jabs to leave the Pole dazed.

Pietrzykowski, who had had to settle for bronze four years earlier, was slumped against the ropes by the end of the round, with Clay having seemingly come close to a knockout, resulting in the judges awarding the American his third unanimous points decision of the competition, as well as the Olympic title.

Clay's victory gave the United States their third gold medal in the ring, leaving them behind only host nation Italy in boxing at the Games.

Clay made his professional debut less than two months later, winning his first 19 professional fights over a three-year period to earn a shot at the world title, which was held by compatriot Sonny Liston. Liston headed into the bout as the favourite, but the Olympic champion caused an upset as Liston was unable to answer the bell for the seventh round. Following his name change, Ali retained the title a year later in a rematch with Liston.

Ali remained unbeaten until 1971, when Joe Frazier beat the then-29-year-old in 'The Fight of the Century' at Madison Square Garden, which was Ali's 32nd professional fight.

Ali continued to fight until 1981, finishing his career just short of his 40th birthday with defeat to Jamaican Trevor Berbick, leaving him with a 56-5 professional record.

Fifteen years after winning gold, Ali claimed in his autobiography that he had thrown his medal into the Ohio River after being refused service at a "whites-only" restaurant, although the story has been heavily disputed, with his biographer insisting that the medal was simply lost. At the 1996 Games in Atlanta, Ali was presented with a replacement during intermission at a basketball game.

The onset of Parkinson's Disease has limited Ali's appearances in public in recent years, but he was well enough to appear at the opening ceremony for the London 2012 Olympics, standing before the flag as it was brought into the stadium 52 years after being crowned Olympic champion.