Winning with opposite coloured bishops

I seldom read a chess book from cover to cover, but Averbakh's "Chess Endings: Essential Knowledge" looks like being an exception. It's also been a fertile source of positions and puzzles for the Chess Tales blog.

Everyone 'well-schooled' chess player knows that opposite colour bishop endings are drawn, but here is a great example from Alexander Kotov - Mikhail Botvinnik, Moscow 1955, that shows this is not always the case:





















Black is a pawn up, but the White king stops the b-pawn advancing and it appears that the White bishop can defend the king side pawns without a problem.

Botvinnik's winning plan involves creating a second passed pawn, his vision to achieve it, sacrificing his extra material is exceptional:

1 ... g5!!; 2 fxg5 d4+!

It's important to keep the advanced passed b-pawn. (Roger: the winning idea, 2 well separated passed pawns in an opposite coloured bishop ending is reasonably well known)

3 exd4 Kg3; 4 Ba3

4 Be7 Kxh4; 5 g6+ Kg4 does not help either.

4 ... Kxh4; 5 Kd3 Kxg5; 6 Ke4 h4; 7 Kf3 Bd5+ and White resigned.

Yuri Averbakh, Chess Endings: essential knowledge