1. Bg8-a2 ! {White is threatening to go to d2 with the king play f4+ and mate with Re6 or Sf6}
1... b5-b4! {1... a3? is a misstep allowing 2. Kd2}
2. Ba2-c4 a4-a3! {2... b3? would be another misstep}
3. Bc4-b3 a3-a2 4. Kc1-b2 {now he goes the other way}
4... a2-a1=Q + 5. Kb2*a1 {Tempo duel is now complete; Black can only forestall.}
5... Bg6-f5 6. Rh6-h5 h7-h6 7. Rh5*f5 #
5... Bg6-f7 6. Bb3*f7 b4-b3 7. Rh6-h5 #
{A case of extended Zugzwang where the pawn mass on the queenside must be accurately handled for White to achieve his plans.}
