Former president Bill Clinton and comedian Billy Crystal are among those due to speak Friday at a memorial in a huge arena in the Kentucky city where Ali -- a three-time world heavyweight champion -- grew up and threw his first punches.
The charismatic Ali, a dazzling fighter and outspoken civil rights activist who became one of the 20th century's most towering figures, died on Friday at age 74 after health problems complicated by a long battle with Parkinson's disease.
"Our hearts are literally hurting. But we are happy daddy is free now," one of Ali's nine children, daughter Hana, wrote on Twitter.
Louisville Mayor Greg Fischer told AFP on Sunday that the city -- whose residents have left flowers, balloons and tributes at Ali's childhood home -- was ready for a massive celebration to honor its most famous son.
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"The Champ was a supernatural figure who crossed all kinds of boundaries, from athletics to arts, to humanitarian activities, from black to white, from Christians to Islam, and he belongs to the world," Fischer said.
The mayor said plans for Ali's last farewell had been in the works for "quite some time," and that the city -- host of horse racing's elite Kentucky Derby, which draws crowds of nearly 200,000 -- was set to "handle big crowds."
After a small family funeral on Thursday, Ali's coffin will be transported Friday through the streets of Louisville, before a private burial and the public interfaith memorial service at the KFC Yum! Center.