Online chess – clearing diagonal for a bishop

Here is a quick snapshot from one of the games I played today:

DDT3000 - deadly-viper, ICC, 3 0, 2009

1. e4 b5 2. d4 a6 3. Bd3 Bb7 4. Nf3 d6 5. O-O Nd7 6. a4 c6 7. Re1 b4 8. c4 a5
9. Nbd2 g6 10. b3 e6 11. Bb2 Bg7 12. Qc2 Ne7 13. Nf1 O-O 14. Ng3 h6 15. Rad1
Rc8 16. h4 h5 17. Ng5 Nf6 18. Qe2 Qc7 19. Bb1 e5 20. dxe5 dxe5

 White to move

21. c5! It may seem that the pawn could become weak on c5, but it is much more important to hit the weak spot on f7. Rfd8 22.Bd3 Rd7 23. Bc4 Rcd8 24. Bxf7+

Kh8 25. Be6 Rxd1 26. Rxd1 Bc8 27. Nf7+ Kh7 28.Nxd8 Bxe6 29. Nxe6 Qb8 30. Nxg7 Kxg7 31. Qc4 Neg8 32. Qe6 Qb7 33. Bxe5 Qa6 34.Rd7+ Kh6 35. Bxf6 Black resigns 1-0

About a year ago in a slow game I missed a similar, but less obvious opportunity:

Jiganchine – Trotchanovich, 2008:

White to move

32. a5! was the best way to continue the attack, since when the black king would try to escape from the kingside – Ba4 would come with decisive effect. I had found this example fairly interesting and even made a youtube video about it.

This also reminded me of an episode from one of my other games that was played even a longer time ago:
Seid – Jiganchine, 2001, BC Closed 2001

Black to move

32… c4! Now Black's pieces can be activated through the c5 square. 33. Bg2 Qc7 34. Ne4
Nd7 35. Bd4 Nc5 36. Bxc5 Bxc5 37. Nxc5 Qxc5 38. Bf1 Bd3 39. Bxd3 Rxd3
This position is an easy technical win for Black. A passed pawn, active pieces and an exposed White king make it almost impossible not to win this endgame.40. Ke2 Rd4 41. Qc3 Qd5 42. Rf3 Rd1 43. Qc2 Rh1 44. Rf2 Qd4 45. Kf3 Rd1 46. Re2
Rd3+ 47. Kg2 c3 48. Kf1 Rd1+ 49. Kg2 Rd2 After the exchanges on d2 the king is too far to stop the pawn 0-1