Stopping a runaway pawn

This was an exceptionally tricky endgame, even before it reduced to 7-men in the position shown here, which arose after Black's 60th move.

Each phase of the ending deserves careful study, starting with the position after the time control. White had a long think then but played the suspect 41 h3 whereas the online engine preferred White with 41 f5. In the next phase Black seemed to improve his position but at a critical moment he allowed the White king to attack his h-pawn and set up a dangerous passed pawn on that file.

The diagram position after 61 h4-h5, at the start of the 7-man ending, shows a very critical situation for Black (the higher-rated player and FM). He failed to see either that it was possible to prevent the White pawn queening, or that there were ways to save the game by precise play after promotion.

Only two moves hold here. The ideas that could have saved the half-point were that Black must either threaten the bishop with check at move 62 or else set up a blockade with a N on f7. The various methods of saving the ending are equally worth study: preventing the promotion, the defence with both knights, and the defence with a single knight. Black, in the game, fell into an inferior version of the latter, but an improved form of it was possible.

Alistair Hill (2159) - James P. Jackson (2343)
British Championship 01.08.2015

1.Nf3 Nf6 2.c4 e6 3.g3 d5 4.Bg2 c5 5.0-0 Nc6 6.d4 Be7 7.dxc5 Bxc5 8.a3 0-0 9.b4 Be7 10.Nbd2 a5 11.b5 Nb8 12.Bb2 Nbd7 13.Rc1 a4 14.Qc2 Qa5 15.Rfd1 h6 16.Bc3 Qb6 17.Qb2 Bc5 18.Bd4 Bxd4 19.Qxd4 Ra5 20.cxd5 exd5 21.Qxb6 Nxb6 22.Nd4 Be6 23.Rc7 Rb8 24.Rb1 Kf8 25.Nxe6+ fxe6 26.Bh3 Ne8 27.Rc3 Ke7 28.e4 d4 29.Rd3 Rd8 30.Rb4 Nc7 31.Rdxd4 Rxd4 32.Rxd4 Rxb5 33.Bf1 Rb2 34.Nc4 Nb5 35.Nxb2 Nxd4 36.Bd3 Kd6 37.f4 e5 38.Kf2 Kc5 39.Ke3 exf4+ 40.gxf4 g5 The players received extra time here. White had a long think. 41.h3? [41.f5 Stockfish online preferred White here. 41...Nc6 42.Bc2 gxf4+ 43.Kxf4 Kd4 44.Bxa4 Ne5 45.Be8 Nc8 46.Bh5 Nd6 47.Bf3 Ndf7 48.Bg4 Nd6 49.Bf5 b5 50.Be6 Nxe4 51.a4 b4 52.a5 Nc5 53.Bf5 [53.Kf5!? ] 53...Nc6 Seems a risky plan? [53...b3!? ] 54.Kg4 Nxa5 55.Kh5 Because now White h-pawn is difficult for knights to handle. 55...Kc3 56.Nd1+ Kd2 57.Nb2 [57.Kxh6? Kxd1-+ ] 57...Nc6 58.Kxh6 Ne5 59.h4 Kc1 60.Kg7 Kxb2 61.h5 61...Ned3?? [61...Nb7! This looks somewhat counter-intuitive but is actually the cleanest way to save the game, avoiding the pitfalls of the knight(s) and pawn versus queen ending. 62.h6 Nd8! In this way (only) the promotion of the h-pawn can be prevented. (Probe says Black can also draw by 62...Nd6 63.h7 (63.Kf6? Nxf5 Several other moves also draw. 64.Kxf5 Nf7 leads to a dead drawn Q ending.) 63...Nxf5+ 64.Kf6 Otherwise Black wins. 64...b3 65.h8Q Comically, 65...Nh6! now holds the draw because knight forks prevent both Qxh6 and Kxe5. So next move Nhg4 gives the knights mutual protection and Black is safe. (Black can also "tough it out" with only one knight if he is very careful: 65...Nc4 66.Kxf5+ Kc2! It is important, compared with the game, that the bishop has been exchanged so that the black pieces have more scope. 67.Qc8 (67.Qh2+ Nd2 The holds the WK at bay and Black threatens to advance the pawn. 68.Qc7+ Kd3! and it seems White cannot win.) 67...Kc3! Keeps the K shielded from checks. (67...Kd3? 68.Qd8+ Kc3 69.Ke4 and White can win. 69...b2 70.Qd3+ Kb4 71.Kd4+- ) 68.Ke4 b2 and now winning the knight comes too late: 69.Kd5 b1Q= ) For example, 66.Qe8 Nhg4+ 67.Kf5 Kc2 68.Qc8+ Kb1 69.Ke4 b2 70.Kd4 Ka1 (70...Nf3+ also holds. 71.Kc3 Ne3! To stop Qf5+ and to meet Qb8 or Qb7 by ...Nd1+. 72.Kd3 Ne1+ (72...Nd5 apparently also holds but it's a risky move for a human.) 73.Kxe3 Nc2+ 74.Kd2 Na3 ) 71.Qa8+ Kb1 72.Kc3 Nf2 Establishes a mutual protection society with a N on d3. 73.Qb7 Ned3 Or Nd1+ (but 73...Nfd3? loses to 74.Qh7 Ka1 75.Qa7+ Kb1 76.Qa4 and Black cannot play Kc1 because of mate on c2.) 74.Qh7 Ka1 75.Qa7+ Kb1 76.Qa4 doesn't win because here Black has 76...Ne1! 77.Kd2 Ned3 ) 63.h7 Nef7 buying enough time to advance the b-pawn 64.Bg6 Ne6+!! (However, 64...b3 loses to 65.Bxf7 Nxf7 66.Kxf7 because a NP on 7th does not draw.) 65.Kxf7 White's pawn will be destroyed in every variation. 65...Ng5+ 66.Kf6 Nxh7+= ; 61...Nb3 62.h6 Nd4! also draws because 63 h7 Nxf5+ is the same as the 61...Nb7 and 62...Nd6 line.] 62.h6 b3 63.h7 Ka2? [63...Kc2 is only marginally longer to mate but the winning process is trickier for White. 64.h8Q b2 65.Qh2+ Kb3 66.Qh1 Kc2 67.Qg2+ Kc3 68.Qf1 Kc2 69.Qe2+ Kc3 70.Qd1 eventually wins with correct play.] 64.h8Q b2 65.Qa8+ White plays very accurately. 65...Kb3 66.Qd5+ Kc3 67.Qa2 Kc2 68.Qc4+ Kd2 69.Bxd3 Nxd3 70.Qb3 Black's situation is clearly hopeless but White was a bit short of time so he played on for a while. 70...Ke3 71.Kf6 Ke4 72.Qc2 Kd4 73.Kf5 Ke3 74.Kg4 Ne5+ 75.Kg3 Nd3 76.Kh2 Kd4 77.Kg1 Ke3 78.Kf1 1-0

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