Although Liston was widely regarded as unbeatable, he lost the title in 1964 to Cassius Clay (Muhammad Ali), who entered as a 7–1 underdog. Liston retired in his corner due to an inflamed shoulder. Controversy followed with claims that Liston had been drinking heavily the night before the fight and had entered the bout with a lame shoulder. In his 1965 rematch with Ali, Liston suffered an unexpected first-round knockout that led to unresolved suspicions of a fix. He was still a world-ranked boxer when he died in mysterious circumstances in 1970. Underworld connections and his unrecorded dates of birth and death added to the enigma.