Thanks, John. This game occurred to me trough an endgame exercise from a program called (how imaginatively) “chess endgame training”. In this exercise I was supposed to find (among other moves) the move 60…a3 as leading to a “draw”. I suspected that it didn’t, therefore I checked and found the nice winning variation mentioned in my above post. Indeed playing 60…b3 was my first choice when given this position. I suppose when Lerner figured the consequences of 60… b3 61.a3!? Kc3! He may not even have bothered to look at 60…a3.     

IMJohnCox wrote on 01/05/07 at 12:32:16:


Yes, I'm not sure if that is exactly what you meant, but I do have a suspicion that one of the things that separates strong players from weaker ones is their ability to recognize that certain constellations are favorable while others are not, without the need to actually calculate the moves

Psakhis-Lerner, Moscow, 1986, 1/2-1/2

I was going through this amazing endgame (see game PGN below) 
http://www.jinchess.com/chessboard/pos=8/8/5KP1/8/pp5N/8/Pk6/8%20b%20-%20-
60...b3!
Here the annotator claimed that black can also draw with 60...a3 61.g7 b3 62.g8Q bxa2:


http://www.jinchess.com/chessboard/pos=6Q1/8/5K2/8/7N/p7/pk6/8%20w%20-%20-
63... White to play

Indeed, how in the world can white do anything against black's threat of queening when his forces are so far away?
With the help of Shedder + tablebases I found that this is not the case and that white can indeed win. If you feel like honing your tactical skills, try solving it without looking at the solution below.



Solution: 
The key is to get the constellation with the queen on d3, the black king on b2 and then bring over the Knight. This can be achieved with a series of checks and a clever triangulation with the queen:
63.Qg2 (63.Qb8 should also work) Kb1 64.Qe4 Kb2 65.Qe2 Kb1 66.Qd3 Kc1! (Now the triangulation trick to get the K to b2) 67.Qc3 Kb1 68.Qb3 Ka1 69.Qd3! Kb2 (and now finally, the knight arrives) 70.Nf5!! (70.Nf3! also works) a1Q 71.Nd4!
http://www.jinchess.com/chessboard/pos=8/8/5K2/8/3N4/p2Q4/1k6/q7%20b%20-%20-&nbs...;
...and Black is curiously helpless:
71...Qb1 72.Qb3 Kc1 73.Ne2+-

Obviously none of this can be envisioned OTB but I believe Lerner's outstanding endgame understanding made him choose the correct 60...b3!. Indeed the way he saved this game (58...b4!!; 61...Kc3!) is just incredible


[Event "It"]
[Site "Moscow (Russia)"]
[Date "1986"]
[Round ""]
[White "Psakhis Lev (ISR)"]
[Black "Lerner Konstantin Z (UKR)"]
[Result "1/2-1/2"]
[Eco "B70"]
[Annotator ""]
[Source ""]

1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 d6 6.Be2 g6 7.Nb3
Bg7 8.O-O O-O 9.Kh1 Be6 10.f4 Na5 11.f5 Bc4 12.e5 Bxe2 13.Nxe2
Ne8 14.fxg6 hxg6 15.e6 Nc6 16.Nf4 Ne5 17.Nd4 Nc7 18.Bd2 Qc8 19.exf7+
Rxf7 20.c3 Qd7 21.Nh3 Rxf1+ 22.Qxf1 Rf8 23.Qe2 Qg4 24.Qxg4 Nxg4
25.Nf3 e5 26.Kg1 e4 27.Nh4 Be5 28.Nxg6 Bxh2+ 29.Kh1 Rf6 30.Bf4
Rxg6 31.Bxh2 Nxh2 32.Kxh2 d5 33.Rd1 Ra6 34.c4 Rd6 35.cxd5 Rxd5
36.Rxd5 Nxd5 37.Kg3 Kf7 38.Ng5+ Kf6 39.Nxe4+ Ke5 40.Nc3 Nf4 41.Kf3
Nd3 42.Nd1 Kd4 43.g4 b5 44.g5 Ne5+ 45.Kf4 Ng6+ 46.Kf5 Nh4+ 47.Kg4
Ng6 48.Kf5 Nh4+ 49.Kg4 Ng6 50.Nc3 a6 51.Kf5 Nh4+ 52.Kg4 Ng6 53.Kf5
Nh4+ 54.Ke6 Kd3 55.Nd5 a5 56.Kf6 Kc2 57.Ne3+ Kxb2 58.Nf5 b4 59.Nxh4
a4 60.g6 b3 61.a3 Kc3 62.g7 b2 63.g8Q b1Q 64.Qg3+ Qd3 1/2-1/2