Five fighters defeated Muhammad Ali: Joe Frazier, Ken Norton, Leon Spinks, Larry Holmes and Trevor Berbick. Larry Holmes was the only fighter to achieve a knockout victory against Ali.
Of the boxers who have defeated Muhammad Ali, three (Spinks, Holmes and Berbick) did so after Ali's thirty-fifth birthday. Although Ali was able to avenge his losses to Frazier, Norton and Spinks, he lost in his final two professional fights. Larry Holmes' victory over Ali in 1980 came by way of Technical Knockout (TKO) in the tenth round, when Ali retired from their fight at Caesar's Palace in Las Vegas, Nevada. Ali was thirty eight years old. Ali's final fight, and his final loss, came in 1981, one month shy of his fortieth birthday.
Muhammad Ali won thirty one professional heavy-weight fights before he lost for the first time to Joe Frazier in New York City in 1971. The loss came by way of unanimous decision. It is widely regarded as one of the most historic fights in boxing history. The fight also set the stage for one of Ali's greatest rivalries, alongside those with heavy-weight greats Liston, Foreman and Norton. Ali was able to defeat Frazier in a rematch three years later.
Larry Holmes stands as the only boxer to have ever forced Ali to retire from a fight.