I've noticed that I have trouble with breakthroughs in pawn endgames. I think it's part blindness, part the avoidance of calculations, and part unwillingness to muck up my tidy pawn chains.
I entered into a pawn endgame where I, as black, had a pawn plus and the opposition.
However, after White played 49.Ke2-d2!?, Black can't win through opposition alone. In some endgames the attacker keeps re-seizing the opposition, pushing the defending king back and finally grabbing material. However here, after 49... Kf3 50. Kd3 for example, White takes the opposition, and after my 49...Kf4 White could have kept up resistance with 50.Ke2!? and repeating the position. Instead, he let me take the opposition and win with the usual opposition technique: 50. Kd3 Kf3 51. Kd2 Kf2 52. Kd3 Ke1 53. Kc2 Ke2 54. Kc1 Kd3 55. Kb2 Kd2 0-1.
The fact that opposition alone here shouldn't win should have been more obvious to me at the time. The following is a classic position of this nature. Black to move:
However, in my game Black still wins in several lines by the breakthrough ...b4! For example, after 49.Kd2:
49... b4! 50. axb4 (50. cxb4 allows Kxd4) 50... a3 51. Kc2 a2 52. Kb2 Kd3 and after White captures the a-pawn Black gobbles all of White's remaining pawns and wins.
I tried to find a similar pawn endgame in my reference books, and also by ChessBase posistion searches, but couldn't find anything. I think this highlights how complex pawn endgames can be...only 4 pawns versus three, and yet this structure may be unique. ChessBase's search functions can be quirky, however. For example, if I searched my blog database, I could find this game using the position, or using the material count, but not both. Weird.