One of the all-time famous blunders. Bronstein is positionally crushed by Petrosian's maneuvering and in the end, in terrible time trouble, is reduced to mechanically moving a Knight back and forth between d4 and c6. Petrosian, with plenty of time, stepped away for a moment, and returning to the board, assumed that Bronstein had played Nc6 again, and moved without noticing that Bronstein had made a different move, attacking the White Queen. Once Bronstein took the Queen off, Petrosian was so horrified that he resigned instantly. An interested spectator picked up the clock, hoping to see if Black could have made the additional 5 moves required to reach the time control. Bronstein's flag fell almost instantly. A double blunder!