Most chess players have a good idea of how to use zugzwang, but how about mutual zugzwang squares? I wonder how many "strong" chessplayers out there in chessland have yet to master this concept. In the following game, had White understood the concept of mutual zugzwang squares, he could have saved himself a painful loss.

In the position above, White played
59. Bd2? which loses by force to
59... Bf8! 60. Be1 Bg7 Now if 61. Bf2 Bf6! Zugzwang!

These two squares, f2 and f6, are the main pair of mutual zugzwang squares. Now White must allow infiltration into his position by Black's bishop or king, which of course spells death.
61. Bc3 Bf6 62. Kg3 Bh8? Correct is
62... Be7 63. Bd2 Bh4+ 64. Kh3 Bf6!

Zugzwang! Now we have a secondary pair of mutual zugzwang squares, d2 and f6.
63. Ba1 Bg7 64. Bb2 Bf8 65. Bc1 Be7 66. Bd2 Bh4+ 67. Kf3 The only move to keep Black from penetrating into his position.
67... Bf6 68. Be3 Kh4 69. Bf2+ Kh3 70. Be3 Bh4 71. Bd2 Kh2 72. Bc3 Kg1 73. Bd2 Bf2 74. Bc1 Kf1! Not 74... Bxd4? 75. Be3+! and White is in the ballgame!
75. Bb2 Be1 Black methodically penetrates deeper into White's position.
76. Ba1 Bd2 77. Kg3 Ke2 78. Kh4 Bxf4 79. Kh5 Bd2 80. Kg6 f4 Returning to Diagram 1, White could have secured the half point with 59.Bc1!! Bf8 60.Bd2! Zugzwang!

We have another secondary pair of zugzwang squares. 60...Be7 61.Be1 Bd8 62. Bg3! Bf6 63. Bf2. Zugzwang! Once again we arrive at the main pair of mutual zugzwang squares, only its Black to move!
0-1
[Muhammad S.]