Foreman's career in the ring lasted 30 years. He won the World Heavyweight Championship twice and fought some of the sport's biggest names. But it was Frazier who struck fear into the young Foreman.
In January 1973, at just 24 years old, Foreman faced Frazier for his first shot at the WBC and WBA titles. Despite his fear, Foreman won the fight in convincing fashion.
"I fought Joe Frazier to become the heavyweight champ of the world for the first time, the great Joe Frazier, the only man I was truly afraid of and that's why I knocked him down six times, I was scared he was gonna kill me."
Foreman shared these thoughts during his interview with ABC Boston.
Foreman's reign as champion didn't last long. Just over 18 months later, he lost his titles to Muhammad Ali in the famous "Rumble in the Jungle". After a shock defeat to Jimmy Young in 1977, Foreman retired and became a preacher.
But the story didn't end there. Foreman made a comeback in 1987, ten years after hanging up his gloves. In 1994, at 45 years old, he knocked out Michael Moorer to become the oldest world heavyweight champion in history.
Frazier's reputation as a nightmare opponent was well-earned. Known for his crushing left hand and incredible strength, he was the first man to beat Muhammad Ali in 1971. Frazier and Ali went on to fight twice more, with Ali winning both rematches.
Sadly, Frazier passed away from cancer in 2011 at the age of 67. He'll always be remembered as one of the greatest heavyweights of all time - and the one fighter who truly scared George Foreman.