It was not just Ali's prowess in the ring that inspired a generation. Barack Obama explained that the fighter's determination to come back to the top of the sport after four years of exile for his refusal to fight in the Vietnam War was the quality he admired the most.

"I was still in grade school when Ali made his extraordinary comeback after nearly four years of exile and later shocked the world by winning his title back," the US president said.

"It was this quality of Ali’s that I have always admired the most: his unique ability to summon extraordinary strength and courage in the face of adversity, to navigate the storm and never lose his way.

"This is the quality I’m reminded of when I look at the iconic photo I’ve had hanging on my wall of the young fighter standing over Sonny Liston.

"And in the end, it was this quality that would come to define not just Ali the boxer but Ali the man — the Ali I know who made his most lasting contribution as his physical powers ebbed, becoming a force for reconciliation and peace around the world."

Former British world heavyweight champion, Lennox Lewis, meanwhile, said that Ali had inspired him when he was a young child to go on and become a champion himself.

"Muhammad Ali inspired me to chase my dreams in and out of the ring. He meant a great deal to me. I kind of fashioned my whole career after him. Watching him on television as a youngster really did something to me," Lewis told The Daily Telegraph.

"I loved his flashiness, I loved what he stood for, like going against America in the Vietnam War. I loved the fact that he always had helpful advice, was a nice man that he was very religious, that he wanted to help people."