notyetagm: Position after 29 ♕d2x♗d5: 29 ... ?
 click for larger viewHere Onischuk (White) was counting on the tactical point that the <UNDEFENDED> Black a8-rook was hanging to his White d5-queen to <INDIRECTLY DEFEND> his White e7-knight (i.e., 29 ... ♕d6x♘e7?? 30 ♕d5x♖a8). But the tactical wizard Shirov (Black) played a much stronger move, 29 ... ♖a8-c8!, forcing White's instant resignation. Position after 29 ... ♖a8-c8! 0-1
 click for larger viewBlack has just moved his <UNDEFENDED> Black a8-rook away from the White d5-queen <WITH TEMPO>, by threatening mate on the c1-square (<WEAK BACK RANK>). Because the Black rook now threatens a <SNAP MATE> with 30 ... ♖c8-c1+, White does not have the time to save his White e7-knight which is no longer protected by the <INDIRECT DEFENSE> mentioned above. <<<The <UNDEFENDED> Black a8-rook was able to move with a <GAIN OF TIME> by threatening mate, meaning that White could -NOT- depend on it being <UNDEFENDED> on the a8-square to <INDIRECTLY DEFEND> the White e7-knight.>>> The Black a8-rook was able to <MOVE FOR FREE> due to the <TEMPO> of the <MATE THREAT>. Onischuk no doubt saw this idea of the <UNDEFENDED> Black a8-rook <MOVING FOR FREE> away from his White d5-queen but probably overlooked that 29 ... ♖a8-c8! was -STILL- possible even though the White e7-knight -APPEARS- to <DEFEND> the c8-square because the White e7-knight has the more important task of <DEFENDING> the White d5-queen from the threat of 30 ... ♕d6x♕d5. So Shirov's masterly 29 ... ♖a8-c8! uses a <MATE THREAT> to <GAIN TIME> to move his <UNDEFENDED> Black a8-rook <FOR FREE> onto the c8-square which only <APPEARS> to be <DEFENDED> by the White e7-knight but is not actually <DEFENDED> because the White e7-knight is <OVERWORKED>. |