Muhammad Ali's funeral is to be held in his hometown of Louisville at 2pm local time (7pm BST) on Friday.
The service, at the KFC YUM! Centre in the Kentucky city, will be open to the public and streamed live on the internet for those unable to attend.
It will be preceded by a Jenazah - an Islamic funeral prayer programme - also for the public at midday on Thursday at the Freedom Hall, where Ali made his professional debut with victory over Tunney Hunsaker in 1960 and fought for the last time in Louisville against Willi Besmanoff a year later.
Among the talkers at "The Greatest's" funeral will be Malcolm X's daughter Attalah Shabazz, wife Lonnie Ali, eldest daughter Maryum, American actor Billy Crystal, former US president Bill Clinton and Recep Tayyip Erdogan, the president of Turkey.
"Everything that we're doing here was blessed by Muhammad Ali, and was requested," said family spokesman Bob Gunnell, who broke the news of the former world heavyweight champion's death at the age of 74 on Friday.
"He wanted the memorial service to reflect his life, and how he lived. He wanted everyone to be able to attend. He was the people's champ, and he wanted the memorial service to reflect that.
"We want this to be inclusive of everyone. That's why we set Freedom Hall - not just with its historical significance - but with the size of Freedom Hall, so that everyone fits in.
"That Muslims and people of all faiths could attend, and perhaps learn more and be like Muhammad Ali, and open their hearts to everybody.
"(We expect) 15,000 people at the Yum! Centre, and 18,000 at Freedom Hall.
"This is not a political statement, this is not about politics, this is about how Muhammad Ali lived his life."