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
Fairy chess piece "pao" and "vao" (derived from the Chinese cannon) and the "mao" (derived from the horse). Those derived from the cannon are distinguished by moving as a hopper when capturing, but otherwise moving as a rider. Pieces from xiangqi are usually circular disks, labeled or engraved with a Chinese character identifying the piece. Pieces from shogi (Japanese chess) are usually wedge-shaped chips, with kanji characters identifying the piece. Fairy pieces vary in the way they move, but some may also have other special characteristics or powers. The joker (in one of its definitions) mimics the last move made by the opponent.