Which boxer defeated Muhammad Ali in the 1973 'Fight of the Year'?

Ken Norton defeated Muhammad Ali in the 1973 bout later recognized by The Ring magazine as the Fight of the Year. Their first meeting took place on March 31, 1973, at the San Diego Sports Arena.

Norton entered as a talented contender, while Ali was rebuilding after his 1971 loss to Joe Frazier. The fight was contested for the NABF heavyweight championship and was broadcast nationally on ABC. Norton used an awkward, effective style built around a low jab, cross-armed defense, and pressure that disrupted Ali's rhythm.

Norton won a 12-round split decision, handing Ali only the second defeat of his professional career. The fight became especially memorable because Ali suffered a broken jaw, although accounts differed over exactly when the injury occurred. Despite the injury, he continued for the remaining rounds.

The loss began one of boxing's most compelling rivalries. Ali won the rematch by split decision in September 1973, and their trilogy ended in 1976 with another disputed decision favoring Ali. Norton remained one of Ali's most difficult opponents.