Today we will analyse an interesting ending from the game J.Yoos-L.Davies, played in the sixth round of this year's B.C. Championship tournament in Vancouver.
In the first diagram White is about to make his 39th move. Although White has the nominal advantage of bishop vs knight, Black's position does not present any cause for alarm. He is well-centralized and has the entry points under control. Indeed, White's bishop is somewhat short of targets, and will have to content itself with restricting Black's movements in the hope that his colleague the king can make something happen. But at the moment that does not look too likely.
39.Bf5 Ne8 40.Be4+ Kd6 41.Bg2 Nc7 42.Bb7 Ne8 43.Be4 Nf6 44.Bg6 Kc6
After some minor sparring we are back where we started. White tries a different tack.
After 45...a6 46.b5+ axb5+ 47.axb5+ Kd6 the draw could be agreed fairly soon.
This aggressive move suggests that Black is playing for a win, or at least keeping that possibility open. Otherwise he might have dug in with 46...Kc7 and if 47.Ka6 then 47...Kb8 48.Bg6 Nd5 49.Kb5 Kc7 50.Kc4 Kd6 51.Bf7 Nf6, when things are looking familiar.
It should be noted that at this point both players were running short of time. This largely accounts for the reversals of fortune that occur over the next few moves.
White's only chance for active play is an attack on his opponent's queenside pawns. He could have prefaced this move with the interesting 47.g3!?, trying to prevent Black from creating a passed pawn, but then 47...Nc3+! 48.Ka6 Nxa4 49.Kxa7 Kc7 leads to yet another drawish position.
47...Nxf2 48.Kxa7 Kc7?
A serious error that should have cost Black the game. Correct was 48...Nd3! when there are two main variations:
A) 49.Kxb6 Nxb4 50.a5 e4 51.Bc4! (not 51.a6? Nxa6 52.Kxa6 e3 53.Bc4 Kc5 and Black wins) 51...e3 52.a6 Nxa6 53.Bxa6 Kd5 54.Ka5 h5 55.Kb4 Ke4 56.Be2 h4 57.g4 (or 57.gxh4 gxh4 58.Kc3 Kf4 59.Kd3 Kg3 60.Bg4 Kf2 and draws) 57...Kf4 58.Kc3 Kg3 59.Kd3 Kxh3 60.Kxe3 Kg3 61.Bf3 h3 62.Ke4 h2 63.Ke3 h1Q 64.Bxh1 Kxg4 with an immediate draw;
B) 49.b5 e4 50.Bg6! (other moves lose) 50...Nc5 51.Bxe4 Nxe4 52.Kxb6 Kd5 (not 52...Nxg3 53.a5 and White wins) 53.a5 Nd6 54.a6 Nc4+ 55.Kb7 Kc5 56.a7 Nb6 57.Ka6 Na8 and the draw is obvious.
A serious error in return. White is perfectly placed to queen his b-pawn, needing only to lever Black's b-pawn out of the way. But he has to do it accurately. He should prevent Black's next move with 49.b5! when the likely continuation is 49...Nd3 50.a5 (only now!) 50...Nc5 (or 50...bxa5 51.b6+ etc.) 51.axb6+ Kd6 52.b7 Nxb7 53.Kxb7 and wins.
Correctly blockading the dangerous White b-pawn. Completely wrong would be 49...bxa5? 50.b5! as in the previous note.
50.Ka6 e4 51.Kxb5 e3 52.Bc4 Ne4 53.Bd3?
This is no time for waiting moves. White can still save the game with 53.Ka6! Kb8 (if 53...Nxg3 54.b5 e2 55.Bxe2 Nxe2 56.Ka7 Nd4 57.b6+ Kc6 58.b7 Nb5+ 59.Ka8 and Black must give perpetual with 59...Nc7+, etc.) 54.Kb6 Nc3 55.a6 e2 56.Bxe2 Nxe2 57.a7+ Ka8 58.g4 Nc3 59.b5 Na4+ 60.Ka6 Nc5+ 61.Kb6 Na4+ and again Black has nothing better than a draw.
53...Nxg3 54.Kc5 e2 55.Bxe2 Nxe2 56.b5 Nf4 57.b6+ Kb7 58.Kb5 (third diagram)
White's connected passed pawns give him a semblance of counterplay, but that's about it.
Black wins cleanly after 58...Nxh3! 59.a6+ Kb8 60.Kc6 Nf4 61.a7+ Ka8 62.b7+ Kxa7 63.Kc7 Nd5+ 64.Kc8 Nb6+ 65.Kc7 Nd7! But the text move does not spoil anything.
59.a6+ Kb8 60.Kc6 Ne6?!
Black is afraid of the advancing White pawns and does not notice the winning knight manoeuvre. After 60...g4 61.hxg4 hxg4 62.a7+ Ka8 63.b7+ (if 63.Kc7 then 63...Nd5+ 64.Kc6 Nxb6, etc.) 63...Kxa7 64.Kc7 Nd5+ 65.Kc8 Nb6+ 66.Kc7 Nd7 Black wins easily.
The final error, after which Black can no longer win. He can still transpose to the previous note with 61...Nf4+ 62.Kc6 Nxh3.
62.hxg4 hxg4 63.Ke4!
White's king correctly heads east in order to deal with Black's pawn.
Neither side can make progress and the draw was agreed here.