This week's problem was composed by the well-known Soviet composer of problems and endgame studies Leonid Ivanovich Kubbel (1891-1942) and brought to us, as have all of these entertaining problems, by Maine player John Gaspar.

White to move and win. (Kubbel, 1910)

The Solution:

The direct approach 1 a7? fails to win after 1 ... Bd5, and the bishop stops the pawn from queening. Similar to The Problem Corner #2, White must keep the Black bishop off the a8-h1 diagonal.

So, White wins with 1 Ne7! Now Black has two choices to get his bishop to the critical diagonal. One choice is 1 ... Bc2 2 Nd5! Winning easily are 2 ... exd5 3 a7 and 2 ... Be4 3 Nf6+, so Black must play 2 ... Ba4 3 Nb4 (not 3 Ne7? Bc2 repeats the position) 3 ... Bd1 4 Nc6! Ba4 5 Nd4 and 6 a7 queens the pawn.

The other option is no better: 1 ... Bd1 2 Nc6! Bf3 (2 ... dxc6? 3 a7 and the pawn queens) 3 Ne5+. If 2 ... Ba4 3 Nd4 is sufficient.