Ali's career started with a gold medal at the 1960 Summer Olympics in Rome. He turned pro that October and quickly climbed the ranks. In his 20th fight, he shocked the world by stopping Sonny Liston to become World Heavyweight Champion.
Ali's career hit a snag in 1967 when he refused to participate in the Vietnam War. The champ was forced to give up his heavyweight title. But he came back strong. In 1974, he reclaimed world honors in the famous 'Rumble In The Jungle' against George Foreman.
Despite his impressive resume, Ali wasn't shy about admitting who he thought could beat him. In a YouTube clip, Ali said:
"I'm scared of him. He's a real champ. [Tyson would have won], I was a dancing master. You are that powerful and so fast, if you hit me [then I hit the canvas]."
Tyson started his pro career in 1985, long after Ali had retired. In 1986, he made quick work of Trevor Berbick to become WBC Heavyweight Champion. At just 20 years old, he became the youngest heavyweight champ ever - a record that still stands today.
Tyson recently returned to the ring in a controversial 8-round contest against Jake Paul. The fight took place at AT&T; Stadium in Arlington, Texas last November. Tyson lost the bout, but it showed he still has drawing power decades after his prime.
While we'll never know how a prime Ali vs. prime Tyson fight would have played out, Ali's words show the respect he had for Tyson's skills and power.