Queen's Gambit Declined, Semi-Tarrasch Defense - Pillsbury Variation

MIGUEL NAJDORF vs. LAJOS PORTISCH
Varna, 1962

1. d4, d5
2. c4, e6
3. Nc3, Nf6
4. Nf3, c5
5. cxd5, Nxd5
6. e3, cxd4
7. exd4, Bb4
8. Qc2, Nc6
9. Bd3, Nxc3
10. bxc3, Nxd4

Black takes advantage of the pin on White's King.

11. Nxd4, Qxd4
12. Bb5+, Ke7

If 12....Bb7, then 13. Bxb7 Qxb7, 14. cxb4 and White is one piece up.

13. 0-0, Qxc3
14. Qe2, Bd6

Not 14....Qxa1 because of 15. Bg5! 

15. Bb2, Qa5
16. Rfd1, Rd8
17. Qh5, f6

If 17....a6, then 18. Qh4+ f6, 19. Bxf6 gxf6, 20. Qxh7+ Kf8, 21. Qh8+ Kf7, 22. Qxd8 and the position favors White.

18. Qxh7, Kf7

If 18....Qxb5, then 19. Qxg7+ Ke8, 20. Qh8+ Ke7, 21. Bxf6+ with an overwhelming attack.

19. Be2 ....

Preparing for an attack on h5.

19. .... Qg5

Black defends the g7 pawn. In the course of the game, Black has underestimated the importance of this defense.  The alternative 19.....Bf8 will not hold because of 20. Bh5+ Ke7, 21. Qg6 with a mating threat at f7.

20. Bc1, Bxh2+
21. Kxh2, Qe5+

Black also threatens the a1 Rook.

22. f4!!, Resigns

The Black Queen is driven away, and there is no stopping White in a mating attack.  If 22...Qxa1, then 23. Bh5+ Kf8, 24. Qh8+ Ke7, 25. Qxg7 mate.