A section of former world champion Floyd Mayweather Jr's heartfelt tribute on Instagram: "Today my heart goes out to a pioneer, a true legend, and a hero by all means! 

"Not a day went by entering the gym that I didn't think of you. Your charisma, your charm and above all, your class are all of the elements that will be greatly missed by myself and the world."

Image source, floydmayweather

Ben Dirs
BBC Sport

"On paper, Ali is the greatest heavyweight in history. The first three-time world champion in boxing's blue riband division - when there was only one heavyweight world champion at any given time - Ali fought all-comers and whupped almost all of 'em."

Read more from Ben here.

No other sportsman in history has been as entertaining as Ali was outside of the ring. We'll flood this live with his best quotes throughout the day - starting with these gems:

• "If you even dream of beating me, you better wake up and apologise."  
•  "I'm so fast that last night I turned off the light switch in my hotel room and was in bed before the room was dark."
• "Will they ever have another fighter who writes poems, predicts rounds, beats everybody, makes people laugh, makes people cry and is as tall and extra pretty as me?"  

Former England football captain David Beckham posts this picture on Instagram, external and writes: "The Greatest there will ever be .... The biggest and the best ..... Rest In Peace."

Image source, DavidBeckham

Image source, Getty Images

Muhammad Ali's achievements are even more incredible when you consider his fighting prime was lost because of his political views.

He spoke out for African-American civil rights in the 1960s and was subsequently stripped of his title and banned from the sport.

Boxing promoter Bob Arum said: "When people saw what he had done for what he believed in - threw away three and a half years of his career and he remained steadfast - he came through all of that bigger and more important than ever before."

Barry McGuigan, the former world featherweight champion, says "everybody wanted to box because of him".

"He was just so amazing in every way," said McGuigan. "More than anything else it was how humble and how brilliantly charismatic he was. He was a beautiful-looking man, a beautiful-looking individual and he had so much compassion. He was the greatest sportsman there has ever been and we were very lucky that he chose boxing."

Eddie Hearn, promoter of current heavyweight champion Anthony Joshua, said: "The Greatest has passed. You shook up the world." 

Remember to send us your memories of Muhammad Ali via #bbcboxing., external And if you have any pictures with the great man, please send them along too. We'd love to see them.

Image source, Getty Images

The trash talk which seems to envelop boxing now is all for one thing: to sell a fight. Yet Ali didn't need to sell his fights - he was a big enough name that people around the world would wake in the dead of night to listen to his bouts over a crackly radio broadcast.

Instead he focused on unsettling his opponents - and arguably nobody was more disconcerted by his antics than Sonny Liston, a brute of a boxer who scared most men. Except Ali.

He taunted Liston in the build-up, bought a bus and painted 'Liston will go in eight' on the side of it before driving it to his opponent's home in the middle of the night and hammering the horn.

Thinking about it, why were we surprised that Liston was a tad shaken?

BBC Sport's Ben Dirs has done a magnificent job of profiling Muhammad Ali's boxing career, and he writes: "A mark of greatness is the ability to evolve and in Ali's case there were four distinct ages: Olympic champion Ali, the innocent boy with a grin; pre-exile Ali, when his feet were a whir, his hands were a blur and nothing could touch him; post-exile Ali, a thicker, slower version with courage to burn; fading Ali, an empty shell of a man whom none of us wanted to see."

Read more here.

Image source, Getty Images

British boxer Anthony Joshua on Instagram:, external "You've inspired the next generation in many different ways! Legacy lives on."

Image source, Anthony_Joshua

Image source, AP

Former WBO cruiserweight champion Johnny Nelson said: "He was the guy I wish I could be. 

"His greatest fight for me was when he fought Cleveland 'Big Cat' Williams, when he beat George Foreman and his amazing fights with Joe Frazier. I don't think that love-hate relationship ever ended. 

"This guy was very humble with a smile. He'd joke with you and say, 'I'm the greatest!', but he knew how good he was. 

"They use the words 'legend' and 'great' too freely in this world; Ali was a true legend and a true great." 

Muhammad Ali fought in England three times, beating Henry Cooper twice (at Wembley and Highbury) and Brian London at Earls Court.

He was actually knocked down by Cooper in their first meeting, an incident which went down in folklore because of the actions of Ali's legendary trainer Angelo Dundee.

Realising his man was struggling, and wanting to buy more time, Dundee called the referee over to point out a tear in his man's glove. It is claimed Dundee made this tear bigger., external

Either way, Ali recovered sufficiently to win with a fifth-round knockout.

Image source, Getty Images

Legendary broadcaster Sir Michael Parkinson interviewed Ali four times and said: "It was not often I was gobsmacked but as he walked across the studio floor I'd never seen a more graceful or beautiful man, he was extraordinary.

"He was a man who could fell you with a blow - kill you maybe - yet he had beautiful hands with long tapering fingers.

"You never saw anyone of 17 stone who moved like he did, he was the biggest star boxing will ever have."

Listen to Parkinson's tribute here.

BBC World Service

For those following from overseas, BBC World Service will be hosting a special Sportshour programme between 10 and 12 BST. So, in effect, a double Sportshour.

And, on BBC Radio 5 live, there will be a special Your Call at 09:00 BST.