power of passed pawn
in the next diagram, you can analize the final game of international tournment of Avellino (Italy) between two players to whom could win it was been category premium (elo 1500 - 1799).
In this position black to move, the danger for balck player is
passed pawn in f but also he has a passed pawn that can assure
draw game. Nevertheless, white player has a rook and against
the threat Te6ch he must prepare a good defense.. After Af6(?),
white player captures the bishop with Te6 and this is the move
of the game that black player has played in zeitnot, understimated
the power ok his passed pawn. If black player had played Af8
draw game was highly probable.
In fact, after 2. Te6 - Rc7 3. Rd5 - a4 4. bxa4 - b3 5. Te2 - Aa3 6. Re6 - b2 7. Txb2 - Axb2 8. f6 - Aa3 9. Rf7 - Rd6 10. Re8 - Re6 11. f7 - Ae7 12. f8=D - Axf8 13. Rxf8 - Rc6, the position is perfectly draw (see the diagram under).
In fact, to promove and queening respective pawns, will occur ten moves for black and ten for white player. So, in dispect the quality sacrifice in middlegame the advanced position of black pawns assures draw game.