Rocky Marciano the only heavyweight boxing champion to retire with an undefeated record
The only heavyweight boxing champion to retire with an undefeated professional record is Rocky Marciano.
Known as “The Brockton Blockbuster,” Marciano held the World Heavyweight Championship from 1952 to 1956 and retired with a perfect professional record of 49 wins and 0 losses (43 of those wins coming by knockout). This feat is particularly remarkable in the heavyweight division, where a single mistake can end a fight instantly, and no other champion in the sport’s highest weight class has managed to step away from the ring having never tasted defeat.
Source:
https://www.youtube.com/watch?v=2HYUOg75doo
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