Boxing legend Muhammad Ali died of "septic shock due to unspecified natural causes", the BBC has reported, citing his family.
Ali died on Friday night at a hospital in Phoenix, Arizona. The 74-year-old had been suffering from a respiratory illness, a condition that was complicated by Parkinson's disease.
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Considered by many to be the best boxer in history, Ali proclaimed himself as the “Greatest of all time” in 1964 and the title stuck.
Although defeated five times in his career, he is often referred to as “The Greatest” and is at the top of most boxing rankings.
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President John Mahama is among the many world leaders to have paid tribute to the fallen boxer, whose funeral will be held on Friday in his hometown of Louisville in Kentucky.
“Sad to hear the passing of Muhammad Ali. He was our hero and truly ‘the Greatest’,” the president said in a Facebook post.