In Louisville, Ky, US boxing great Muhammad Ali recalled Mandela as a symbol of forgiveness who overcame racial injustice and inspired others to "reach for what appeared to be impossible."
The two met twice and exhibits at the Muhammad Ali Center in Louisville include a photograph of the men together, their hands clenched into fists as if they're boxing.
"He made us realize, we are our brother's keeper and that our brothers come in all colors. What I will remember most about Mr. Mandela is that he was a man whose heart, soul and spirit could not be contained or restrained by racial and economic injustices, metal bars or the burden of hate and revenge," Ali said.
Actor Morgan Freeman, who portrayed Nelson Madela in 2009's "Invictus", said the world had lost one of the true giants of modern history.
"Today the world lost one of the true giants of the past century. Nelson Mandela was a man of incomparable honor, unconquerable strength, and unyielding resolve - a saint to many, a hero to all who treasure liberty, freedom and the dignity of humankind. As we remember his triumphs, let us, in his memory, not just reflect on how far we've come, but on how far we have to go. Mandela may no longer be with us, but his journey continues on with me and with all of us."
