"I continue to strive to be the very best but what got me to come here is the AIDS," Holyfield, wearing a green safari suit, told reporters in Addis Ababa late on Tuesday. "If we don't find a cure to this, we'll be extinct."

Everton Boland, chief executive of promoters Golden Globe, said a substantial percentage of the money raised would go to charity, but he declined to discuss the fighters' purses.

"If you want to talk about money, we ain't up to that part yet," Boland said. "Ain't no boxer fighting for free," according to Reuters.

Organisers said a group set up by 22 African First Ladies to fight HIV/AIDS is the only charity chosen so far to receive funds from the fight, but that they are considering others.

Holyfield's manager Ken Sanders said the 46-year-old, who some in the sport have argued is too old to still be fighting, plans to have another world title fight in September, possibly against WBA champion Nikolai Valuev.
 
The huge Russian won a majority points decision against Holyfield in December in Zurich, ending the American boxer's hopes of becoming the oldest ever title-holder.
Retta -- a 35-year-old based in Washington DC -- left the Ethiopian capital for the United States at 16 and has since won 18 professional fights and lost three.

He compared the planned July 26 bout against Holyfield in Addis Ababa with 1974's legendary "Rumble in the Jungle" clash in Kinshasa between Muhammad Ali and George Foreman.

"I feel so tremendous," Retta told the news conference. "Fighting Evander is like Ali fighting in Africa."