It is impossible to imagine us ever seeing a sportsman or woman to rival Muhammad Ali as the greatest of them all.

To see the great man celebrate his 70th birthday on Tuesday is a milestone many thought was impossible after he was diagnosed with Parkinson’s disease a generation ago.

But Ali is still a fighter. And he has never lacked the courage to go the distance. He has tackled impossible odds his whole life. From standing up to racism and having the strength of character to refuse to go to Vietnam, to upsetting the odds so many times in the ring, Ali has never stopped surprising people.

In 1964 he became world heavyweight champion after being given no chance against Sonny Liston. Not only did he win an epic fight but he destroyed Liston in the re-match.

It was those victories over Liston that first propelled Ali into a world star. But not the last time he would defy impossible odds. His trilogy against the late Joe Frazier is part of boxing folklore and arguably his greatest achievement was when he overcame George Foreman in The Thriller in Manilla.

For me Ali has always been the greatest and always will be. My own personal memory was when I met him over 20 years ago and even in the early stages of Parkinson’s Ali still had that unmistakeable aura that only the greats possess.

He also showed me that he has a heart of gold by giving us an hour of his time when we arranged to film him meeting two unknown brain damaged boxers in South London. Earlier in the day he’d been to visit Michael Watson recovering in hospital from his fateful fight with Chris Eubank. Ali was so genuine, so humble that day and it was wonderful to see how kind he was to his fellow boxers less fortunate than himself.

Ali truly is the greatest. Always has been and always will be.