In chess, a blunder is a critically bad mistake that severely worsens the player's position by allowing a loss of material, checkmate, or anything similar.
Although blunders are most common in beginner games, all human players make them, even at the world championship level.
[3] One technique formerly recommended to avoid blunders was to write down the planned move on the score sheet, then take one last look before making it.
Steinitz replied 32...Rxh2+ and Chigorin immediately resigned (in light of the blind swine mate 33.Kg1 Rdg2#), losing the match.
Petrosian (White), enjoys a clear advantage with strong knights, active rooks and great mobility while Black's position is congested.
Bronstein (Black) has for the last seven turns made aimless knight moves, Nc6–d4–c6–d4, while White had kept strengthening his position.
This game between Miguel Najdorf and Bobby Fischer from the 1966 Piatigorsky Cup is an example where a player in a bad position breaks under the pressure.
Korchnoi could have prevented this by moving his g-pawn (but not the h-pawn because 39.h3 or h4 leads to 39...Rc1+ 40.Kh2 Nf1+ 41.Kg1 Nfg3+ 42.Kh2 Rh1#), providing an escape square for his king.
[16] In this example, from a tournament in Biel in 1987, the game did not result in a loss for the blunderer, but led to an embarrassing draw for the British GM Murray Chandler.
Chandler realized that after 54.gxh6+ Kxh6 he will be left with the considerable material advantage of a rook pawn and bishop against a bare king.
?, but instead of the expected 54...Kxh6, Polgar played 54...Kh8, leading to almost the same king, bishop, and rook pawn versus bare king situation as Chandler had calculated that he would avoid, and the small difference that White has two rook pawns rather than one has no effect on the result.
Commentators, including American grandmaster Yasser Seirawan, voiced concerns about Kramnik's intentions and the situation became more uncertain as the game went on with 32.Nxe6 Bxe3+ 33.Kh1 Bxc1 34.Nxf8, turning it into a likely draw.
From ChessBase: "Kramnik played the move 34...Qe3 calmly, stood up, picked up his cup and was about to leave the stage to go to his rest room.
At least one audio commentator also noticed nothing, while Fritz operator Mathias Feist kept glancing from the board to the screen and back, hardly able to believe that he had input the correct move.
Fritz was displaying mate in one, and when Mathias executed it on the board, Kramnik briefly grasped his forehead, took a seat to sign the score sheet and left for the press conference.
Chess journalist Alexander Roshal attempted to explain the blunder by saying that the mating pattern of a queen on h7 protected by a knight on f8 is extremely rare and not contained in a grandmaster's automatic repertoire.
[citation needed] The World Chess Championship 2024 was decided in dramatic fashion in the 14th and final game of match due to a blunder by Ding Liren as White.
Played at the USSR Chess Championship in 1937, held in Tbilisi, this game featured a double blunder.
Ragozin was planning to trade rooks with 40...Rc7 41.Rxc7 Bd6+ as this would transpose the game into a winning bishop versus knight endgame for Black.
?, and saw almost immediately that this loses to 27...R8xf4!, in effect winning a piece since taking the rook gives Black a forced mate: 28.gxf4 Nxf4 (threatening Qg2#) 29.Rg1 Qxh2+ 30.Kxh2 Rh3#.
Aronian had seen 27...R8xf4, but playing quickly to avoid time trouble, he thought that White could strike back with 28.gxf4 Nxf4 29.Ra8+ since both 29...Kf7 and 29...Kh7 lose to the knight fork 30.Ng5+.
The sixth game of the World Chess Championship 2014 in Sochi between Magnus Carlsen and Viswanathan Anand also featured a double blunder.
Carlsen adopted the space-gaining Maróczy Bind setup against the Kan Variation of the Sicilian Defence, and accepted a set of isolated doubled pawns in return for active play.
After an early queen exchange he soon developed a commanding position and appeared to have excellent winning chances.
(with a discovered attack on the g4-rook) 27.Rxg8 Nxc4+ (zwischenzug) 28.Kd3 Nb2+ 29.Ke2 Rxg8 leads to Black picking up two extra pawns and gaining excellent winning chances.
[29] In this 1902 game between Ignatz von Popiel and Georg Marco, the black bishop on d4 is pinned to the rook on d7, and there are no additional friendly pieces to come to its defense.
[29] In this game played in Budapest in 1955 between György Négyesy and Károly Honfi, Black saw that White's c3-knight is stopping ...Rd1#.
Correct is 58.Qg8+ winning the bishop (58...Bf7 blocks the king's escape square on the seventh rank, allowing 59.Qd8 which leaves two mate threats, 60.Qd7# and 60.Qd6# which cannot both be prevented (59...Rxd4 60.Qd6#; 59...Rxg4 Qd7#).
In the game between Victor Korchnoi against Geert Van der Stricht [nl], at the 2003 European Team Championship,[31] Black seems helpless against White's kingside threats.
He missed, however, the fact that the White king was lined up with Black's rook, so 38...gxh6+ would have been discovered check and 39.Qxh6# is illegal.