George Foreman says boxing legend "Muhammad Ali made you love him."
Former world heavyweight champion Foreman lead tributes to Ali, who died at the age of 74.
He told BBC Five Live: "Muhammad Ali made you love him.
"If you dislike him you wanted more than anything to see him again so you could dislike him again.
"Beauty is how you would describe him. Muhammad Ali was what I call beautiful. He has been something special.
"The man was the greatest. Forget about boxing, he was one of the greatest men to appear on television, to appear in the media.
"He was the greatest."
Champion Foreman was sensationally beaten by Ali in the Rumble in the Jungle in Kinshasa, Zaire [now DR Congo] 42 years ago, which is still regarded as one of sport's most iconic moments.
Ali looked out on his feet but pounced in the eighth round, putting Foreman on the canvas and the fight was stopped by the referee.
Foreman added: "Little did I know I would be facing something greater than a boxer.
"He stood the test. He took everything I had and gave back worse. I loved the man. I wanted to beat him and knock him out but I loved the man.
"He called me Frankenstein's monster. He was only saying that because it was true. I was a monster, I was a monster."
When asked about Ali's fight with Parkinson's disease, Foreman said more research had to be done to find a cure.
"Muhammad Ali fought the best he could," he added.