Roberto DeVicenzo, 1968 Masters (Golf)

Widely regarded as one of the nicest guys in professional golf, the 45-year-old Argentinean began the final round two shots behind the leader and shot a sizzling 65. His playing partner and marker, Tommy Aaron (in pro events your playing partner keeps your score and you keep his), mistakenly gave him a par 4 on the 17th rather than a birdie 3, and DeVicenzo hastily signed the incorrect card and submitted it to the official scorer. Because the Rules of Golf state that a score card may not be changed after it has been turned in, the 4 counted. Bob Goalby finished tied with DeVicenzo’s actual score, but because of the error, Goalby won the Masters by one shot.
This incident, a “rules disaster,” was perhaps even more tragic than a standard on-course collapse — claiming not one but three victims: DeVicenzo; Aaron, who would donate a vital organ if it could undo his blunder; and Goalby, whose victory is forever tarnished as resting on a technicality. For his part, DeVicenzo accepted his fate with good humor. At the awards ceremony, he said, “What a stupid I am!”