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
Chess piece relative value minor pieces are usually better than a queen because of their greater mobility, and the extra pawn is not important enough to change the situation . Three minor pieces are almost as strong as two rooks . Two minor pieces plus two pawns are almost always as good as a queen. Two rooks are better than a queen and pawn . Many of the systems have a 2-point difference between the rook and a minor piece, but most theorists put that difference at about points, see The exchange (chess)#Value of the exchange. In open positions, a rook plus a pair