A pawn sacrifice at the center of the board is sometimes necessary to open up a central file. This post gives us an example of an attack while the opponent King is not yet castled.
BORIS SPASSKY vs. ALEX AFTONOMOV
Leningrad, USSR, 1949
1. d4, d5
2. c4, dxc4
3. Nf3, Nf6
4. e3, e6
5. Bxc4, c5
6. 0-0, e6
7. Qe2, Nc6
8. Nc3, b5
9. Bb3, Bb7
10. Rd1, cxd4
11. exd4, Nb4
12. d5!! ....
White intends to open the e-file.
12. ... N4xd5
13. Bg5, Be7
14. Bxf6, gxf6
Not 14.....Bxf6, Black would lose a piece after 15. Nxd5 Bxd5, 16. Rxd5 ...
15. Nxd5, Bxd5
16. Bxd5, exd5
17. Nd4, Kf8
18. Nf5, h5
Black thought that White's Queen is going to h5, so he 'blocks' the square. White's reply surprises him.
19. Rxd5!! Qxd5
20. Qxe7+, Kg8
21. Qxf6!! Resigns
Black cannot handle the simultaneous threats at e7 (Knight fork) and mate at g7.
To view the game in PGN format, you may visit Spassky vs. Aftonomov.