Taken from a recent Blitz game. White played 50. Qxf3 and eventually lost. What do you think, was his decision to take Black's queen correct? If your answer is yes, how should he have continued after 50. ... exf3?
It turns out that White's decision to trade queens was correct. In fact, after 50. ... exf3, White is winning! But White must be careful, because after 51. Se3 a4 52. Sc2?, Black wins!
White's knight is tied to c2 to prevent the a-pawn from promotion, and White's king cannot attack Black's g&f pawn without moving out of the g-pawn's critical squares! While White's king is moving back and forth on the 1st rank, and White's knight is guarding the a-pawn's queening square from c2, Black's king has all the time in the world to take White's pawn on f4 and then move to h2 to escort the g-pawn to g1. White's king even has to watch out for a king&pawn mate!
Carlos mentioned the winning move for White: 52. Sxe5!
If Black takes on e5, he can do nothing to prevent the promotion of White's c-pawn, and his a-pawn is too slow (White will take with check!). If instead Black decides to advance his a-pawn right away, White moves his knight to b4, and now starts his pawn avalanche with his f-, d- and c-pawn! If Black choses not to push the a-pawn at all, moving in his king instead, the result is the same. Meanwhile, without the support of the Black king, the White king successfully holds Black's g/f pawns in check (if you forgive the pun).
So remember: do not hesitate to sacrifice your one remaining piece for the benefit of your pawn storm!