Chess games are won because one side makes a mistake, and these mistakes, however subtle, are usually dubbed blunders. They can occur at any stage of the game, though they are most likely to occur in time pressure or in very difficult positions. This game, Indian GM Abhijeet Gupta vs. young Ukrainian GM Anton Korobov, was played in the super-strong AICF-AAI Cup in India.  Black’s mistake occurs with a casual move: 10… Qe8, completely overlooking a discovered attack which won a pawn. Black managed to get it back, but possibly in time trouble, went awry in a late stage of the game.