Daily chess puzzle

As my regular readers will know, one of my habits is to cut out or copy positions I find difficult, store them away, and subsequently in spare time try to solve them, whether or walks, planes, trains or at other times. Today’s problem is one such.

Black to play and win

Grandelius v Lupulescu, 21.11.2015, seen in Malcolm Pein’s Daily Telegraph column

Solution

I found this quite hard, and, when I found the solution, surprising: surprising that 1 …f4! was so strong.

I found it, having tried the two ways to exchange on d4, and the pin Qc5 first, more or less by elimination, though Purdy’s examine all biffs also helped.

White’s queen is tied to defending the Nd4, and  the key is that it is forced to move to e4: 2Qe4. This lets Black’s Queen into c3, hitting the Nd4 a third time, and also threatening to mate on b2 or a1 if the N moves: so White’s position collapses.

Other ways of finding the solution, apart from examine all biffs, are Purdy’s other tools of looking for jump-biffs: Rd8-d1 is one, and Bf6-b2 is another: highlighting the pin; and noting the White’s Q’s tie to the Nd4.