Undermining (also known as removal of the guard, or removing the defender) is a
chess tactic
In chess, a tactic is a sequence of moves that each makes one or more immediate threats ─ that is, a check, a material threat, a checkmating sequence threat, or the threat of another tactic ─ which culminates in the opponent being unable to ...
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.
Example
Kramnik–
Topalov in the seventh round of the 2004
Linares chess tournament
The Linares International Chess Tournament ( Spanish: ''Torneo Internacional de Ajedrez Ciudad de Linares'') was an annual chess tournament, usually played around the end of February, which takes its name from the city of Linares in the Jaén p ...
reached the diagrammed position with White to play. The black knight on a4 is defended only by the black pawn on b5. White undermined the knight with 1. Bxb5. The game continued 1... Rxb5 2. Rxa4, with a net gain of a pawn for White.
Black may attempt 1...Nxb2??, disposing of the unguarded knight and hoping for 2.Kxb2 Rxb5+ to regain the lost pawn. However, after 2.Rb3 Black can only save the knight with 2…Rxb5 3.Rxb5, leaving White an
exchange up instead of just a pawn.
See also
*
Deflection (chess)
Deflection in chess is a tactic that forces an opposing piece to leave the square, rank or file it occupies, thus exposing the king or a valuable piece. It is typically used in the context of a combination or attack, where the deflected piece i ...
References
{{chess
Chess tactics
Chess terminology