Muhammad Ali may be a shadow of his former all-powerful self, but his 70th birthday will today bring in congratulations and best wishes from his legions of fans all over the world, who remain touched by his extraordinary life.
His professional career is only part of the story. Despite being arguably the most celebrated boxer in history, Ali is one of that elite group of sportsmen whose personal qualities transcend his chosen pugilist field. Through his unique strength of character, he has been able to touch on politics, religion, sports and celebrity. Here, at a glance, are just some of the landmark dates in a life that continues to defy any expectation or generalisation:
17 January 1942: Cassius Marcellus Clay is born in Louisville, Kentucky.
1954: Takes up fighting aged 12 after a white Louisville police officer takes him under his wing after his bicycle is stolen.
1954 - 60: His amateur career brings him a reported 100 wins and five losses.
1960: Wins gold medal at the Rome Olympics, in the Light Heavyweight category.
Ali claims in his later autobiography that he throws his medal in the Olympics, after being refused service in a ‘whites-only’ restaurant.
He returns to Kentucky for his first professional fight.
1960 - 1963: Enters a pugilistic purple patch, with a fighting record of 19 wins, no defeats, including 15 knockouts.
1963: Makes first visit to England, to fight Henry Cooper. The popular Brit knocks him down, but loses to Clay when the fight is stopped.
1964: Clay wins his first World Heavyweight Championship, beating the strong favourite Sonny Liston. Clay has taunted his opponent in the lead-up to the fight, describing what will become his signature battle-cry: "I will float like a butterfly and sting like a bee."
1964: Clay has agreed to keep the news of his religious conversion quiet until after the fight. Immediately it is over, he confirms that he has joined the Nation of Islam and takes the name Muhammad Ali. A year later, he will convert to Sunni Islam, before later settling on Sufism.
1964: Marries first wife, cocktail waitress Sonji Roi. The marriage lasts two years.
1965 - 1967: Ali defends his title nine times and becomes universally recognized as world heavyweight champion after outpointing World Boxing Association (WBA) champion Ernie Terrell in fifteen rounds on 6 February 1967. Ali often proclaims his invincibility in verse and boasts: "I am the greatest!"
1965 - 1967: Ali defends his title nine times in all, finally taking on WBA champion Ernie Terrell. This is an ugly fight, following pre-match taunting between the pair. Terrell insists on referring to his opponent as "Clay" and Ali responds by calling Terrell "Uncle Tom". Ali finally defeats Terrell in 15 rounds, becoming the undisputed world heavyweight champion.
Meanwhile, his proactive religious beliefs make him an increasingly polarising figure. He appears at Muslim rallies and his remarks reveal him to be against inter-racial relations in one breath - "No intelligent black man or black woman in his or her right black mind wants white boys and white girls coming to their homes to marry their black sons and daughters" - but also passionately against discrimination of all kinds: "Hating people because of their color is wrong. And it doesn't matter which color does the hating. It's just plain wrong."
1967: Ali is publicly arrested and castigated for his refusal to be drafted to serve for his country in the Vietnam War, based on his religious beliefs and lack of support for the campaign. In one of the era's most renowned remarks, he states: "I ain't got no quarrel with them Viet Cong... No Viet Cong ever called me nigger."
His remarks serve as torchpaper for anti-war protestors, but authorities take a dimmer view. Ali is stripped of his boxing licence, his world title and prevented from fighting for another four years while his appeal against conviction for felony makes its way to the US Supreme Court.
1967: Ali marries Belinda Boyd. The couple have four children and are married for ten years.
1971: The Supreme Court reverses his conviction. Soon after, he meets Joe Frazier in Madison Square Garden for 'The Fight of the Century'. Both are undefeated fighters with a claim to the world title. After a contest that lives up to the all the hype, Frazier knocks Ali to the floor in the 15th and final round.
October 1974: Ali participates in a globally-hyped fight with George Foreman in Zaire, billed "The Rumble in the Jungle". Millions of viewers around the world tune in to watch Ali take on the younger, fitter Foreman who is used to beating his rivals quickly, often with a knockout. But Ali tires out his opponent, using his speed to dance around him and wearing him down with "rope-a-dope" tactics, until he finally knocks him out in the eighth round, becoming the world champion in one of history's great sporting upsets.
October 1975: Ali takes on Frazier for the third time, this occasion being billed "The Thriller in Manila" by ambitious promoter Don King. Ali builds up the ante again with pre-fight bravado, including this bon mot: "It will be a killa... and a chilla... and a thrilla... when I get the gorilla in Manila."
Sure enough, his prophecy comes true, but not until the 15th and final round, when Frazier's trainer stops the fight.
1975: Ali releases his autobiography, humbly titled: "The Greatest: My Own Story"
1977: He marries actress and model Veronica Porsche, and they have two daughters, including Laila, who will go on herself to become a boxer.
1978: Ali defeats Leon Spinks, becoming the first boxer to win the heavyweight championship three times.
1979: He announces his retirement, with only three defeats among 59 victories. He loses two further WBC fights in the next two years, before retiring permanently from the ring.
1984: It emerges that Ali is suffering from a type of Parkinson's Syndrome, a condition of the nervous system affecting mobility and speech.
1986: Ali marries Yolanda. The couple celebrated their silver wedding anniversary last November, and have one adopted son, Amin.
1991: During the first Gulf War, he travels to Iraq and meets with Saddam Hussein to try to negotiate the freedom of hostages.
1996: When We Were Kings, all about the Rumble in the Jungle, wins an Oscar for Best Documentary.
1996: Ali lights the flame at the opening ceremony of the Atlanta Olympics. The IOC present him with another gold medal, to replace the one he threw away all those years before.
1999: He is named Sportsman of the Century by Sports Illustrated, and Sports Personality of the Century by the BBC, who invite him to London to accept his prize. It transpires Ali has received more votes than the four other leading contenders combined.
Ali's physical frailty is evident, but he is surrounded and protected by other professional boxers for whom he clearly remains an inspiration.
2001: Actor Will Smith earns an Oscar nomination for his portrayal of the legend in the film Ali, directed by Michael Mann.
2002: Ali named a UN Messenger Of Peace, and visits Afghanistan.
2005: Opens the Muhammad Ali Center in his hometown of Louisville, a foundation for social activism, which aims to promote respect, responsibility and personal growth.
2005: Receives the Presidential Citizens Medal from President George Bush.
17 January 2012: Muhammad Ali celebrates his 70th birthday with a party in his hometown.
Former world heavyweight champion Lennox Lewis is a guest, and says of his idol: "What he's done outside the ring - just the bravery, the poise, the feeling, the sacrifice. He's truly a great man."
Ali’s younger brother, 68-year-old Rahaman Ali, is also present and recalls his brother as a young child:
"As a little boy he (said) he would be the world's greatest fighter and be a great man."
Look back at Muhammad Ali's amazing life and career in pictures in our special Slideshow: