"I got nothing against no Viet Cong. No Vietnamese ever called me nigger."

With those words, Muhammad Ali, the American boxing legend who died at the weekend, defined his anti-Vietnam War posture in the mid-1960s.

Ali surely would have felt vindicated about his resolute stand as Washington's ties with Hanoi came full circle: Days before he died, US President Barack Obama lifted the embargo on arms sales to Vietnam, having arrived to a tumultuous welcome.

Ali's career was all the more remarkable for the prejudices he had to overcome. Seven years before he won his first heavyweight title, writer Kyle Onstott released the best-selling book, Mandingo.

Set in Alabama, it is a tale of the slave trade that celebrates the black physical form while denying the community even the right to life. The handsome Ali often said Cassius Clay - as he was known before he converted to Islam - was his "slave name".

As a boxer, Ali was called The Greatest. Just how much greater he was will never be known; a sporting ban he endured for refusing military conscription kept him out of the ring for years.

In another era, the career of cricket's biggest legend, Don Bradman, was similarly interrupted by World War II.

Mr Obama keeps a pair of Ali's gloves in his private study, a nod to the role the boxer's life and message played in his own ascent as the first black president. Ali's name was "as familiar to the downtrodden in the slums of South-east Asia and the villages of Africa as it was to cheering crowds in Madison Square Garden", the President said.

Ali, who stood for the peaceful face of Islam, also influenced the American civil rights movement led by Martin Luther King.

And it is a fair guess that golfer Tiger Woods, who is of African-American and Asian ancestry, would have faced much more racial prejudice if it weren't for the adoration Americans felt for Ali in his later years.