The semi-endgame position shown in the first diagram arose an open tournament held in Italy a number of years ago. White is on move. As always the key question is: who stands better and why? I think the most accurate assessment is that White has an edge but Black will manage to neutralise it. With careful play on both sides one could easily expect a handshake and a draw within the next ten moves or so. All very reasonable except that this is the game D.Gurevich-Korchnoi, Bratto 1998. Both players are in the running for first place and both players are grandmasters so today there will be no agreement to a draw until the position is a draw. And with time running short on both sides, things are going to get bumpy...
17.Rc2 Nb8
The immediate 17...a5 was also possible: 18.Na4 (not 18.b5 Nb4! 19.axb4 axb4 20.Rac1 Rxc3 21.Rxc3 bxc3 22.Rxc3 Rd5 23.Rb3 and White is now on the shady side of the draw) 18...axb4 (or 18...Na7!? 19.Rxc8 Nxc8 20.bxa5 bxa5 21.Nd4 Bf8 with equality) 19.Nxb6 Rc7 20.axb4 (definitely not 20.Rac1 b3! 21.Rxc6? Rxc6 22.Rxc6 b2 and Black wins) 20...Rb8 21.Na8 Rcc8 22.Rac1 Rxc8 23.Rxc6 Rxc6 24.Rxc6 Bxb4 25.Rc7+ Kg6 and neither player will make much progress from here.
18.Rac1 a5 19.Na2
White is playing for a win. He could practically force a draw with 19.Na4 Rxc2 20.Rxc2 axb4 21.axb4 Bxb4 22.Nxb6.
19...Rxc2+ 20.Rxc2 axb4 21.Nxb4 Bc5!?
Black also seems to be playing for a win. He can achieve a compact defensive position after 21...Bxb4 22.axb4 Na6! 23.Rc6 (23.b5 Nc5=) 23...Nxb4 24.Rxb6 Nd5 25.Rb7+ Ne7 26.Nd4 Rd6. The next few moves see White play on the slight insecurity of the bishop's post on c5.
22.Rc4 Nd7 23.a4 Ra8 24.Nd3 e5 25.Nd2 Ke6 26.e4 Kd6 27.Nb3 Ba3 28.a5!?
The point of White's preceding manoeuvres, but it is all bluff.
28...Bc5?!
There is nothing wrong with 28...bxa5; for example, 29.Ra4 Bc5 30.Nxa5 Kc7! and Black has no problems.
29.Rc2
White cannot achieve anything by exchanging on c5 because Black's king is well-placed to deal with White's a-pawn. So he marks time and waits for a better opportunity.
29...g6 30.Rd2 Ke7? (second diagram)
Black can defend his position with 30...Kc6!; for example 31.axb6 Bxb6 32.Nb4+ Kc7 33.Nd5+ Kc6 34.Rc2+ Kd6. Perhaps Korchnoi was keeping the tension as a way of playing for a win. But after the text move the game takes a big turn in White's favour.
31.Ndxc5! bxc5
No better is 31...Nxc5 32.Nxc5 bxc5 33.Ra2! c4 (or 33...Kd6 34.Kd3 Kc6 35.Kc4 Ra6 36.g4! and Black will eventually succumb to zugzwang; for example, 36...Ra7 37.a6 Kb6 38.Ra3 h6 39.Rb3+! Kc6 40.Rf3, etc.) 34.Kd2 Kd6 35.Kc3 Kc5 36.Rd2! Rb8 37.Rd5+ Kc6 38.f3! Rb3+ 39.Kxc4 Rb2 40.Rc5+ Kd6 41.Rb5 Rxg2 42.Rb6+ Ke7 43.a6 Ra2 (43...Rxh2? 44.Kb3!) 44.Kb5 Kd7 45.Rxf6 and the rest will just be a matter of technique.
32.Kd3 Rb8 33.Kc4 Rb4+ 34.Kc3 Rb7 35.a6
Also possible was 35.Rd5 Rc7 36.Kc4 winning the c-pawn.
35...Ra7 36.Kc4 Ra8 37.Kb5!
Definitely not 37...Ra2 Kd6 38.a7 Kc6 39.Ra6 Nb6+ and Black is suddenly better.
37...Ke6
Or 37...Rb8+ 38.Kc6 Rc8+ 39.Kb7 Rb8+ 40.Kc7 Rxb3 41.Rxd7+ Ke6 42.Rd6+ Ke7 43.Rc6! Ra3 44.Kb6 Rb3+ 45.Kxc5 Ra3 46.Kb6 Rb3+ 47.Kc7 and White wins.
38.Na5 Rc8
If 38...Nb8 White wins neatly with 39.Rd8! Nxa6 40.Rxa8 Nc7+ 41.Kc6 Nxa8 42.Kb7! trapping the knight.
39.Nb7?!
In some time pressure White does not notice that he wins quickly after 39.a7 Ra8 40.Ka6. But the text does not spoil anything.
39...c4 40.Rc2?!
On the last move of the time control White commits another inaccuracy, and a more serious one this time. He could still decide matters quickly with 40.a7! c3 41.Rd6+ Ke7 42.Rc6 Ra8 43.Nd6! Kd8 44.Nc8! However this was not easy to calculate, especially in time pressure.
40...c3 (third diagram)
Both sides have reached time control and Korchnoi has typically managed to scrape up counterplay in the form of his passed c-pawn. But with more time available for reflection Gurevich finds a beautiful winning line that involves the immediate surrender of his biggest asset: his passed a-pawn!
41.a7! Ra8 42.Rxc3 Rxa7 43.Nd8+!
The beginning of a forced manoeuvre to drive Black's king offside. This enables White's king to take over.
43...Kd6 44.Rd3+ Kc7 45.Ne6+ Kb8
No better is 45...Kc8 46.Rc3+ Kb8 47.Kc6 Rb7 48.Kd6 Nb6 49.Nc5 Nc8+ 50.Ke6 Rb6+ 51.Kf7 with a decisive attack on Black's kingside pawns.
46.Kc6 Kc8 47.Rc3 Ra6+?
Losing immediately, but everything else lost eventually.
48.Kb5+ 1-0
The immediate 17...a5 was also possible: 18.Na4 (not 18.b5 Nb4! 19.axb4 axb4 20.Rac1 Rxc3 21.Rxc3 bxc3 22.Rxc3 Rd5 23.Rb3 and White is now on the shady side of the draw) 18...axb4 (or 18...Na7!? 19.Rxc8 Nxc8 20.bxa5 bxa5 21.Nd4 Bf8 with equality) 19.Nxb6 Rc7 20.axb4 (definitely not 20.Rac1 b3! 21.Rxc6? Rxc6 22.Rxc6 b2 and Black wins) 20...Rb8 21.Na8 Rcc8 22.Rac1 Rxc8 23.Rxc6 Rxc6 24.Rxc6 Bxb4 25.Rc7+ Kg6 and neither player will make much progress from here.
18.Rac1 a5 19.Na2
White is playing for a win. He could practically force a draw with 19.Na4 Rxc2 20.Rxc2 axb4 21.axb4 Bxb4 22.Nxb6.
19...Rxc2+ 20.Rxc2 axb4 21.Nxb4 Bc5!?
Black also seems to be playing for a win. He can achieve a compact defensive position after 21...Bxb4 22.axb4 Na6! 23.Rc6 (23.b5 Nc5=) 23...Nxb4 24.Rxb6 Nd5 25.Rb7+ Ne7 26.Nd4 Rd6. The next few moves see White play on the slight insecurity of the bishop's post on c5.
22.Rc4 Nd7 23.a4 Ra8 24.Nd3 e5 25.Nd2 Ke6 26.e4 Kd6 27.Nb3 Ba3 28.a5!?
The point of White's preceding manoeuvres, but it is all bluff.
28...Bc5?!
There is nothing wrong with 28...bxa5; for example, 29.Ra4 Bc5 30.Nxa5 Kc7! and Black has no problems.
29.Rc2
White cannot achieve anything by exchanging on c5 because Black's king is well-placed to deal with White's a-pawn. So he marks time and waits for a better opportunity.
29...g6 30.Rd2 Ke7? (second diagram)
Black can defend his position with 30...Kc6!; for example 31.axb6 Bxb6 32.Nb4+ Kc7 33.Nd5+ Kc6 34.Rc2+ Kd6. Perhaps Korchnoi was keeping the tension as a way of playing for a win. But after the text move the game takes a big turn in White's favour.
31.Ndxc5! bxc5
No better is 31...Nxc5 32.Nxc5 bxc5 33.Ra2! c4 (or 33...Kd6 34.Kd3 Kc6 35.Kc4 Ra6 36.g4! and Black will eventually succumb to zugzwang; for example, 36...Ra7 37.a6 Kb6 38.Ra3 h6 39.Rb3+! Kc6 40.Rf3, etc.) 34.Kd2 Kd6 35.Kc3 Kc5 36.Rd2! Rb8 37.Rd5+ Kc6 38.f3! Rb3+ 39.Kxc4 Rb2 40.Rc5+ Kd6 41.Rb5 Rxg2 42.Rb6+ Ke7 43.a6 Ra2 (43...Rxh2? 44.Kb3!) 44.Kb5 Kd7 45.Rxf6 and the rest will just be a matter of technique.
32.Kd3 Rb8 33.Kc4 Rb4+ 34.Kc3 Rb7 35.a6
Also possible was 35.Rd5 Rc7 36.Kc4 winning the c-pawn.
35...Ra7 36.Kc4 Ra8 37.Kb5!
Definitely not 37...Ra2 Kd6 38.a7 Kc6 39.Ra6 Nb6+ and Black is suddenly better.
37...Ke6
Or 37...Rb8+ 38.Kc6 Rc8+ 39.Kb7 Rb8+ 40.Kc7 Rxb3 41.Rxd7+ Ke6 42.Rd6+ Ke7 43.Rc6! Ra3 44.Kb6 Rb3+ 45.Kxc5 Ra3 46.Kb6 Rb3+ 47.Kc7 and White wins.
38.Na5 Rc8
If 38...Nb8 White wins neatly with 39.Rd8! Nxa6 40.Rxa8 Nc7+ 41.Kc6 Nxa8 42.Kb7! trapping the knight.
39.Nb7?!
In some time pressure White does not notice that he wins quickly after 39.a7 Ra8 40.Ka6. But the text does not spoil anything.
39...c4 40.Rc2?!
On the last move of the time control White commits another inaccuracy, and a more serious one this time. He could still decide matters quickly with 40.a7! c3 41.Rd6+ Ke7 42.Rc6 Ra8 43.Nd6! Kd8 44.Nc8! However this was not easy to calculate, especially in time pressure.
40...c3 (third diagram)
Both sides have reached time control and Korchnoi has typically managed to scrape up counterplay in the form of his passed c-pawn. But with more time available for reflection Gurevich finds a beautiful winning line that involves the immediate surrender of his biggest asset: his passed a-pawn!
41.a7! Ra8 42.Rxc3 Rxa7 43.Nd8+!
The beginning of a forced manoeuvre to drive Black's king offside. This enables White's king to take over.
43...Kd6 44.Rd3+ Kc7 45.Ne6+ Kb8
No better is 45...Kc8 46.Rc3+ Kb8 47.Kc6 Rb7 48.Kd6 Nb6 49.Nc5 Nc8+ 50.Ke6 Rb6+ 51.Kf7 with a decisive attack on Black's kingside pawns.
46.Kc6 Kc8 47.Rc3 Ra6+?
Losing immediately, but everything else lost eventually.
48.Kb5+ 1-0
Dmitry Gurevich is not in the first rank of grandmasters but he has a respectable record against Viktor Korchnoi: +2 -2 =7.
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