Former boxing champ Muhammad Ali is said to be in "grave condition" in a Phoenix-area hospital Friday afternoon as the 74-year-old has been battling respiratory issues.
NBC News was among the media outlets that confirmed Ali's condition. The 74-year-old Ali has been suffering from Parkinson's disease since 1984. Parkinson's has weakened Ali, and he has been rarely seen in public in the last year.
His last public appearance was in September at a function at the University of Louisville.
Ali, born Cassius Clay, is from Louisville, Ky., and has a cultural center in his name in the Kentucky city.
Scripps affiliate ABC 15 in Phoenix confirmed that a medic was called to Ali's home on Tuesday. Reports of Ali's health became public Thursday, as his family said he was in the hospital for a brief stay.
Ali is widely considered the greatest boxer in history. Ali compiled a 56-5 record as a heavyweight. He also had three separate stints as heavyweight champ.
He was named by Sports Illustrated as the Sportsman of the 20th Century, and was awarded with the Presidential Medal of Freedom by President George W. Bush in 2005.
His career was not without controversy. Ali had his boxing license suspended for three years after objecting to serving the US military in the Vietnam War. Ali was sentenced and fined for draft dodging, but later had his conviction overturned after a Supreme Court ruling.
Ali has nine children and a wife of 30 years.