(1) Botvinnik,M - Bronstein,D [D71]
Wch19-Moscow (23), 1951

1.d4 Nf6 2.c4 g6 3.g3 c6 4.Bg2 d5 5.cxd5 cxd5 6.Nc3 Bg7 7.Nh3 Bxh3 8.Bxh3 Nc6 9.Bg2 e6 10.e3 0-0 11.Bd2 Rc8 12.0-0 Nd7 13.Ne2 Qb6 14.Bc3 Rfd8 15.Nf4 Nf6 16.Qb3 Ne4 17.Qxb6 axb6 18.Be1 Na5 19.Nd3 Bf8 20.f3 Nd6 21.Bf2 Bh6 22.Rac1 Nac4 23.Rfe1 Na5 24.Kf1 Bg7 25.g4 Nc6 26.b3 Nb5 27.Ke2 Bf8 28.a4 Nc7 29.Bg3 Na6 30.Bf1 f6 31.Red1 Na5 32.Rxc8 Rxc8 33.Rc1 Rxc1 34.Nxc1 Ba3 35.Kd1 Bxc1 36.Kxc1 Nxb3+ 37.Kc2 Na5 38.Kc3 Kf7 39.e4 f5 40.gxf5 gxf5 41.Bd3 Unfortunately, I sealed

41...Kg6 Here I had to seal the move. The plan is obvious. One bishop should be placed on d6, after White has to play Bb1, exchange the pawns on d5 and win pawn d5. For twenty minutes I was thinking which was stronger: 42.Bd6 or 42.Bb1. Finally, I decided to choose 42.Bd6.

42.Bd6 [ I found that after 42.Bb1 (the move I did not seal) 42...Nc6 ( If Black chose 42...fxe4 the game opens up after 43.fxe4 dxe4 44.Bxe4+ Kg7 and White's bishops obviously prevail. An interesting variation was found by Flohr: 45.Bxb7 Nxb7 followed by followed by Kc3-c4-b5-a6-b6 and the 'a'-pawn eventually queens.) 43.exd5 exd5 44.Ba2 Nab4 ( or 44...Ne7 45.Bh4 ) 45.Bb3 Black loses a pawn.]

42...Nc6 43.Bb1 Kf6 The previous two moves had been found the best and they were made immediately upon the resumption. However, Black's last move was not the only solution. All night I was trying to find the way to continue the game. Only at 8 o'clock in the morning I was lucky to find a remarkable idea which I employed during the adjournment. If Bronstein had suspected about the surprise move, he would have found the line [ 43...Na7 honestly I did not find this move during my analysis. 44.exd5 exd5 45.Ba2 b5 46.a5 b4+! 47.Kd3 Nb5 48.Be5 Nac7 49.Kc2 Kf7 50.Kb3 Na6 thus drawing the game and, most likely, becoming the 7th World Champion. However, after the natural 43.Kf6 an unplesant surprise lay in store for him:]

44.Bg3!! Zugzwang! [ 44.exd5 exd5 45.Ba2 Ke6 and White cannot make headway]

44...fxe4 [ Now 44...Nab4 is met by 45.Be5+! and Black's King is pushed to g6, after which White wins by ( In passing I would note that 45.Bc7 would only lead to a draw after 45...dxe4 46.fxe4 fxe4 47.Bxe4 Nd5+= ) 45...Kg6 46.Bd6 Na6 47.exd5 exd5 48.Ba2 ]

45.fxe4 h6 46.Bf4 h5 47.exd5 exd5 48.h4 Nab8 49.Bg5+ Kf7 50.Bf5 Na7 [ More resistant was 50...Ne7 but White had a good choice anyway: 51.Bxe7 Kxe7 52.Bg6 Nc6 53.Bxh5 Na7 54.Kb4 Nc6+ 55.Kb5 Nxd4+ 56.Kxb6 ]

51.Bf4 Nbc6 52.Bd3 Nc8 53.Be2 Kg6 54.Bd3+ Kf6 55.Be2 Kg6 56.Bf3 N6e7 [ or 56...N8e7 57.Bg5 Nf5 58.Bxd5 Nfxd4 59.Be4+ Kf7 60.Kc4 ]

57.Bg5 Here Bronstein resigned. Although Black still has an extra pawn, he loses because of the zugzwang, the second zugzwang in this game. [ The continuation could be 57.Bg5 Nc6 58.Bxd5 Nd6 59.Bf3 Kf5 60.Bc1 b5 61.Bxc6 bxc6 62.a5 ] 1-0