Boxing Legend Muhammad Ali Placed on Life-Support.

The 74-year-old boxing great is fighting respiratory issues that are complicated by the Parkinson's that he was diagnosed with in the 1980s, the people told The Associated Press on Thursday.

The New York Post and the International Business Times cited a report on the Radar Online website that said Ali had been placed on life support after he was rushed to a hospital in Arizona because of breathing problem.

Radar Online quoted "an insider" as saying, "Doctors are telling the family that it likely won't be long until he passes away."

Meanwhile his fans has taken time to request for prayers for the Champion. Puff Diddy posted a picture of himself with the legend and captioned it; "(placed on life support) we'ar praying for the champ!!!.

Ali's last public appearance was in April at the "Celebrity Fight Night" gala in Arizona, a charity that benefits the Muhammad Ali Parkinson Center.

At the height of his career, Ali was known for his dancing feet and quick fists and his ability, as he put it, to float like a butterfly and sting like a bee.

Ali, who lives in Phoenix, was admitted to hospital in December 2014 with what was believed to be a mild case of pneumonia.

Doctors determined he had suffered a severe urinary tract infection, for which he received further treatment in January 2015.

Nicknamed "The Greatest," he retired from boxing in 1981 with a 56-5 record. Ali's diagnosis of Parkinson's came about three years after he retired.

Ali, born in Louisville, Kentucky, as Cassius Marcellus Clay Jr., changed his name in 1964 after his conversion to Islam.