Undermining (chess) Undermining (chess) Undermining (also known as removal of the guard, or removing the defender) is a chess tactic in which a defensive piece is captured, leaving one of the opponent's pieces undefended or under-defended. The opponent has the unpalatable choice of recapturing or saving the undefended piece. A possible response is to sacrifice the piece whose defense was undermined before capturing the piece which just took the defender. Kramnik–Topalov in the seventh round of the 2004 Linares chess tournament reached the diagrammed position with White to play. The black knight on a4 is defended only by the black pawn on
History of chess a disadvantage, as the other player would have a long period to analyze before having to make a reply when the game was resumed. Preventing access to a chess set to work out moves during the adjournment would not stop him from analyzing the position in his head. Various strange ideas were attempted, but the eventual solution was the "sealed move". The final move before adjournment is not made on the board but instead is written on a piece of paper which the referee seals in an envelope and keeps safe. When the game is continued after adjournment, the referee