Actor Will Smith and former boxing world champion Lennox Lewis will serve as pallbearers together with six other people during Muhammad Ali's funeral Friday, a spokesman said.
The charismatic Ali, a dazzling fighter and outspoken civil rights activist who became one of the 20th century's towering figures, died Friday at age 74 after health problems complicated by a long battle with Parkinson's disease.
Smith, who played the title role in Michael Mann's film "Ali" (2001), became close to the boxing legend after the filming.
Lewis, who was born in Britain, is considered one of the greatest boxers of the last 25 years, having won several world titles in the 1990s and 2000s.
The two celebrities will carry Ali's coffin together with six family members and close family friends, family spokesman Bob Gunnell said.
The funeral ceremony is set to take place on Friday in Ali's hometown of Louisville, Kentucky in front of a huge crowd. It will be broadcast around the world.
The funeral will follow a procession through the streets and will be preceded on Thursday by a family funeral and an Islamic prayer service held in the 18,000-seat Freedom Hall.
The Louisville funeral is aimed at sending a universal message of peace and tolerance, according to organizers.
Ali died in Phoenix, Arizona, where he had recently lived. His body was returned to Louisville by private plane on Sunday.
He will be buried at Louisville's Cave Hill Cemetery.
It's not every day that a king and a president get bumped from giving speeches. But it's happened for Muhammad Ali's memorial service in Louisville, Kentucky, on Friday.
Turkish President Recep Tayyip Erdogan and King Abdullah II of Jordan had been scheduled to speak at the service at the KFC Yum! Center.
Ali family spokesman Bob Gunnell said Monday that two other speakers are going to be added to the current programme, meaning there won't be room for foreign dignitaries.
Gunnell says both their offices were "gracious and understood."
He says the names of the two additional speakers will be revealed later.
Ali died last Friday in Arizona following a long battle with Parkinson's disease. He was 74.
Muhammad Ali and his family never seriously considered donating the boxing great's brain for research, according to the doctor who treated him.
"Not really," was Dr. Abe Lieberman's answer when he was asked Monday if submitting the brain for research was discussed.
Lieberman said he didn't think boxing contributed to Ali's contraction of Parkinson's disease but he couldn't be "a hundred percent" certain.
The doctor spoke at a news conference at the Muhammad Ali Parkinson Center at the Barrow Neurological Institute in Phoenix.
Lieberman was among those who diagnosed Ali in 1984. The doctor said he believes Ali had the disease earlier, when he fought Larry Holmes in 1980.
Ali thought the Holmes fight did serious damage.
In an interview, Ali said that if he had known "Holmes was going to whip me and damage my brain, I would not have fought him. But losing to Holmes and being sick are not important in God's world."
Asked Monday if Ali blamed boxing for the disease, Lieberman said the fighter didn't think that way. He said Ali never regretted his boxing career and, as a devout Muslim, believed it was God's will that he experience the illness and help others to combat it.
The day before his star-studded funeral, members of Muhammad Ali's Islamic faith will get their chance to say a traditional goodbye to the Champ.
Bob Gunnell, a spokesman for Ali's family, announced Monday that a Jenazah, a traditional Muslim funeral service, will be held at Freedom Hall at noon Thursday. It will be open to all.
They chose the venue both because it seats 18,000 and because it holds historical significance for the hometown hero. Ali fought, and won, his first professional fight there in 1960.
Gunnell said Ali, who converted to the Islamic faith in the 1960s, started planning his own funeral nearly a decade ago. Gunnell said he wanted his services "to reflect his life and how he lived" with a heart open to people of all colors and creeds.