(Adds background on career, impact) By Ian Simpson June 3 (Reuters) – Former world heavyweight champion Muhammad Ali was close to death in a Phoenix-area hospital on Friday, a source close to the family said, as speculation swirled about his health. Ali, one of the best-known figures of the 20th century, was hospitalized this week for a respiratory ailment. Family spokesman Bob Gunnell has said that Ali, 74, was in fair condition, but media reports have said he was in rapidly failing health.