BBC Radio 5 Live

World cruiserweight champion Tony Bellew is one of the many from the boxing world interviewed on 5 live this morning.

"He was the ultimate hero. It's heartbreaking news to wake up to. The greatest sportsman of all-time in my opinion. He transcended the sport and this is a sad day. 

"I hope something can be named after him. He can never be replicated."

President Obama added: "He wasn’t perfect, of course. For all his magic in the ring, he could be careless with his words, and full of contradictions as his faith evolved.

"But his wonderful, infectious, even innocent spirit ultimately won him more fans than foes – maybe because in him, we hoped to see something of ourselves.

"Later, as his physical powers ebbed, he became an even more powerful force for peace and reconciliation around the world.

"We saw a man who said he was so mean he’d make medicine sick reveal a soft spot, visiting children with illness and disability around the world, telling them they, too, could become the greatest.

"We watched a hero light a torch, and fight his greatest fight of all on the world stage once again; a battle against the disease that ravaged his body, but couldn’t take the spark from his eyes."

Current United States president Barack Obama was emphatic in his assessment of Muhammad Ali, saying: "He was The Greatest.  Period."

A statement added: "But what made The Champ the greatest – what truly separated him from everyone else – is that everyone else would tell you pretty much the same thing. 

"Like everyone else on the planet, Michelle and I mourn his passing. But we’re also grateful to God for how fortunate we are to have known him, if just for a while; for how fortunate we all are that The Greatest chose to grace our time."

Here is a highlights package of tributes to Ali from boxers past and present, featuring some classic archive clips.

Golf's iconic figure pays tribute to the world sporting legend.

BBC World Service

Muhammad Ali was ridiculously photogenic, which makes this collection of intimate portraits by his personal photographer even better...

Music legend Sir Paul McCartney recalls that legendary meeting with Ali at Miami Beach, Florida on their first visit to America in 1964.

"Dear Muhammad Ali. I loved that man. He was great from the first day we met him in Miami, and on the numerous occasions when I ran into him over the years. 

"Besides being the greatest boxer, he was a beautiful, gentle man with a great sense of humour who would often pull a pack of cards out of his pocket, no matter how posh the occasion, and do a card trick for you. The world has lost a truly great man. Love Paul."

Is Muhammad Ali the planet's most recognisable sportsman? Ali's death is topping the news agenda everywhere, it seems...

Image source, Japan Times

British boxer Chris Eubank Jr, the current British middleweight champion, with his tribute.

As America wakes up to the sad news, here's how the Washington Post website looks. There's some fascinating content, including the quote from George Foreman that a part of him has passed with the loss of Ali.

Image source, Washington Post

Former American president Bill Clinton met the great man many times and pays his tribute.

Image source, Getty Images

There are some amazing first-hand accounts of Muhammad Ali on the Louisville Courier-Journal website.

Lawrence Montgomery Sr, now 81, recalls how Ali was devoted to his craft from an early age. 

“He told me, ‘Lawrence, I am going to be the heavyweight champion of the world,’” Montgomery said., external “I said, ‘You must be losing your mind.’ He said, ‘Just you wait and see.'"

“He would put on his boxing outfit and run to Chickasaw Park and back before school. Then he wouldn’t get on the bus to school – he would run beside it. He ran every place. Every time you saw him, he was just running."

Montgomery also gave young Cassius his first job. He hired the teenager, who was eight years younger, to babysit for his children. “I didn’t have to pay him,” Montgomery recalled. “He just wanted boloney sandwiches,, external I made sure I had plenty in the refrigerator.”

What a picture this is. They don't come much bigger than these two do they? And it is from the great Pele's Instagram., external The Brazilian football icon also wrote this moving tribute: 

"The sporting universe has just suffered a big loss. Muhammad Ali was my friend, my idol, my hero. 

"We spent many moments together and always kept a good connection throughout the years. The sadness is overwhelming. I wish him peace with God. 

"And I send love and strength to his family." 

BBC Radio 5 Live

Wladimir Klitschko - one of the best heavyweights of all time - has been paying his tributes to Muhammad Ali on a special BBC Radio 5 live programme. Have a listen...

BBC Monitoring

Nikolai Valuev, a former professional boxer and two-time WBA heavyweight champion, now a member of the Russian parliament: "It should be said that Muhammad Ali was, is and will remain an idol and a hero for the whole boxing world… There are plenty of great boxers but few of those who have left a trace."

There is a compilation of the many fabulous items of Ali audio magic available for you to savour from the BBC.

Click here to see it all

Malcolm Turnbull, the Australian Prime Minister, with his tribute.

Perhaps Muhammad Ali's most famous fight of them all was against George Foreman - a bout which was named 'Rumble in the Jungle'.

BBC Radio 5 live and the BBC Sport website will be looking back at that incredible night in Zaire later in a special Rewind at 21:00 BST.

George Foreman, looking back on the fight, recalled: "Muhammad Ali didn't have the best punch, he wasn't the strongest, but he was the toughest human being I ever had an encounter with. This I'm certain of.

"He wasn't saying a lot but in round three I hit him with a hard shot to the side and he fell on me and said: 'That all you got, George?!' That scared me, I knew there was going to be trouble then."