In the early 90’s, Tommy Morrison was on the role of his life. Rocky V came out and he won a number of big fights. The man with 42 knockouts beat George Foreman in 1993 for the vacant WBO heavyweight Title. Morrison (48-3-1) beat Tim Tomashek to retain the title and was on his way to face WBC Champion Lennon Lewis. That was before one of the biggest upsets in boxing history took place.
Facing Michael Bentt in October 1993, Morrison was knocked down three times in the first round, losing via TKO. The result costed Morrison an $8 million payday against Lewis, who he ultimately faced and lost to in 1995. Bentt (11-2) only fought once after that fight, losing the title to Herbie Hide. He was forced to retire after suffering brain injuries from the fight.
Check out this classic upset, via Top Rank.