The funeral is to be held in his hometown of Louisville on Friday.
The British boxer, who became the undisputed world heavyweight champion after beating Evander Holyfield in 1999, was on Monday night named as a pallbearer - as was Smith, who was nominated for an Academy Award and a Golden Globe for his portrayal of Ali in the 2001 film.
Lewis said of Ali this week: “He was like family, like a father. He is going to be forever missed and always remembered. Words cannot begin to describe the loss we all face in the passing of one of the greatest citizens this world has ever known. Boxing has lost its greatest ambassador and the world has lost one of its greatest voices.”
The other pallbearers will be Jerry Ellis –the brother of Jimmy Ellis, Ali’s former sparring partner and fellow world heavyweight champion – and Ali’s cousins John Grady and Jan Wadell, nephew Ibn Ali, former brother-in-law Komawi Ali and a family friend, John Ramsey.
The memorial service will be open to the public and streamed live on the internet for those unable to attend.
Among the speakers at the funeral will be Malcolm X’s daughter Attallah Shabazz, wife Lonnie Ali, eldest daughter Maryum, American actor Billy Crystal, the former US president Bill Clinton and Recep Tayyip Erdoğan, the president of Turkey.
“Everything that we’re doing here was blessed by Muhammad Ali and was requested,” said the family spokesman Bob Gunnell. “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.
“This is not a political statement. This is not about politics. This is about how Muhammad Ali lived his life.”
This article was written by Mark Dobson, for theguardian.com on Monday 6th June 2016 23.35 Europe/Londonguardian.co.uk © Guardian News and Media Limited 2010