Friends and sports stars have tweeted their tributes to Muhammad Ali, who passed away at the age of 74.
George Foreman, who famously fought against Ali in 1974 in "The Rumble In The Jungle", tweeted that "a part of me slipped away, the greatest piece".
Speaking to the BBC, Foreman said: "Muhammad Ali was one of the greatest human beings I have ever met. No doubt he was one of the best people to have lived in this day and age."
Boxing professionals were quick to pay tribute to the man who referred to himself as "the greatest".
Former world heavyweight champion Frank Bruno hailed his "inspiration, mentor, friend".
Boxing champion Floyd Mayweather Jr told Fox News: "There will never be another Muhammad Ali.
"The black community all around the world, black people all around the world, needed him. He was the voice for us. He's the voice for me to be where I'm at today.
"I just want to thank Muhammad Ali and his family for being such strong people. You will always be missed. My prayers go out to Ali and his family."
Ali's biographer Thomas Hauser told the BBC that Ali was "beautiful inside and beautiful outside". He tweeted that Ali's death was "the passing of a legend".
Retired Irish boxer Barry McGuigan, who speaking to the BBC remembered Ali's participation in the civil rights movement, tweeted his tribute: