FATAL or fateful error
Jose Capablanca vs. David Janowski in San Sebastian 1911. 53…Qe8?? losing the game, the tournament and became the favourite contender for Lasker’s world title. Lajos Portisch-Anatoly Karpov, San Antonio, 1972 25…Kh8?? 26. Rd5 1-0 (if Qc7 then Bd4+-)