Washington (AFP) - "I am America. I am the part you won't recognize. But get used to me -- black, confident, cocky," Muhammad Ali once said.
The grandson of a slave and an admirer of Malcolm X, Ali was a fiercely talented boxer who dazzled the world with his skills.
But the three-time heavyweight champ and Olympic gold medalist, who died on Friday at age 74, was also a major figure in the US civil rights movement who dazzled the world with his fierce words.
In the 1940s and 1950s, Louisville, Kentucky -- Ali's hometown on the Ohio River -- was a world of divisions: segregated schools, churches, public spaces. Two Americas, one white and one black.
While Ali is now hailed as a global icon, whose role as a messenger of peace deepened as his Parkinson's disease deprived him of his physical powers, the legendary fighter was once seen by Americans as a radical, an outspoken agitator.
"I'm the heavyweight champion of the world, but right now there are some neighborhoods I can't move into," he said after his first victories in the ring -- at the Rome Olympics in 1960, and his initial heavyweight title in 1964.
Defiant under the bright lights, and in front of the cameras for all to see and hear, the gifted boxer courted more and more controversy with his daring statements, many of them delivered in his signature rhyming style.
Ali derided Joe Frazier as an "ugly, dumb gorilla" and the "white man's champion" before his 1975 victory in the "Thrilla in Manila" -- one of many sharp-tongued taunts of his opponents over the years.
He would live to regret some of those statements: in his personal tribute to Ali, US President Barack Obama on Saturday noted the fighter "could be careless with his words, and full of contradictions as his faith evolved."
- Ali and Malcolm X -
In the early 1960s, Ali -- then still known as Cassius Clay -- developed an intense friendship with Malcolm X, the fiery minister and activist who recruited the fighter to join the Nation of Islam.
Ali's first impression of Malcolm X? "He was fearless. That really attracted me."
Their relationship was a heady mix of sports, race and politics, at a time of social upheaval in America.
"Under Malcolm's tutelage, (Ali) embraced the world stage, emerging as an international symbol of black pride and black independence," wrote Randy Roberts and Johnny Smith in their book, "Blood Brothers, The Fatal Friendship Between Muhammad Ali and Malcolm X."
The men later had a major falling out amid deep divisions within the Nation of Islam -- a split that eventually led to the assassination of Malcolm X in 1965 by three of the movement's members. He was 39.
"I wish I'd been able to tell Malcolm I was sorry, that he was right about so many things," Ali said decades later.
"If I could go back and do it over again, I would never have turned my back on him."
- 'A man who fought for what was right'-
In the mid 1960s, the boxer converted to Islam and abandoned what he called his "slave name" Cassius Clay for Muhammad Ali.
The year 1967 marked a turning point: he refused to serve in the US armed forces headed to war in Vietnam.
"My conscience won't let me go shoot my brother, or some darker people, or some poor hungry people in the mud for big powerful America," Ali said.
"And shoot them for what? They never called me nigger, they never lynched me, they didn't put no dogs on me, they didn't rob me of my nationality, rape and kill my mother and father... Shoot them for what? How can I shoot them poor people? Just take me to jail."
His words sent shock waves across America. Ali, a hero to some, was a traitor to others. He polarized the nation.
He avoided prison time but was stripped of his heavyweight crown and banned from boxing for years.
"Muhammad Ali shook up the world. And the world is better for it. We are all better for it," Obama -- America's first black president -- said Saturday.
Ali "stood up when it was hard; spoke out when others wouldn't," he said.
Veteran civil rights activist Jesse Jackson summed up Ali's influence in just a few words: "A champion in the ring, a hero beyond the ring."
Republican presidential hopeful Donald Trump was one of the first to pay tribute to Ali, saying on Twitter that he was a "truly great champion and a wonderful guy."
But just a few months ago, Ali -- ever the outspoken activist -- slammed Trump's proposal to temporarily ban all Muslims from entering the United States after the Paris and San Bernardino attacks.
"I believe that our political leaders should use their position to bring understanding about the religion of Islam," the fighter said.
And in a direct jab at the billionaire, Ali emphasized that throughout his long and colorful life, he had "never been accused of political correctness" -- blunting an argument Trump often makes to diminish his opponents.