Korchnoi's victory over Kasparov in Round 1 of the semifinals

Viktor Korchnoi (who defected from the Soviet Union in 1976) burned the midnight oil, reached into his bag of tricks, and won the first game of his tension-packed semifinal match in the World Chess Championship Candidates' competition against Gari Kasparov, the 20-year-old Soviet chess wizard.

The winner of this match, which is being held at the Great Eastern Hotel in London, will be the first player to score 61/2 points, with a victory counting as one point and a draw as half a point. Whoever triumphs will then meet the winner of the other semifinal between Vassily Smyslov, a former world titlist from the Soviet Union, and Zoltan Ribli of Hungary. And the winner of the final match will have earned the right to challenge World Champion Anatoly Karpov of the USSR in a title match next year.

This first game pitted strength against strength. Korchnoi, the strongest Blackside Queen's Indian Defense player playing today, challenged Kasparov, who has been destroying all comers in this opening with his own special patent, 5. P-QR3. (Regular readers will recall his annihilation of Lajos Portisch in an earlier column.) A well-prepared Korchnoi surprised Kasparov with 7. . . . P-N3, which anticipates a White Kingside attack and blunts its edge by preparing the fianchettoed fortress for the Black King.

The strategy was completely successful, as Kasparov, deprived of his favorite motif, had difficulty coming up with a workable plan. The time consumed by the players after White's 17th move tells the story. Kasparov has taken almost two hours to Korchnoi's four minutes. (The players were each allowed 21/2 hours to complete 40 moves.)

Kasparov could find nothing better than to play for a win of a pawn, which he was unable to maintain. The result was a tattered pawn structure, which gave Korchnoi an opportunity to display his consummate endgame artistry. Queen's Indian Defense Kasparov Korchnoi 1. P-Q4 N-KB3 2. P-QB4 P-K3 3 N-KB3 P-QN3 4. N-B3 B-N2 5. P-QR3 P-Q4 6. PxP NxP 7. P-K3 P-N3 8. B-N5 ch P-B3 9. B-Q3 B-N2 10. P-K4 NxN 11. PxN P-QB4 (a) 12.B-N5 Q-Q3 13. P-K5 (b) Q-Q2 14. PxP (c) O-O 15. PxP PxP 16. O-O Q-B2 17. B-N5 BxP (d) 18. B-KR6 B-N2 19. BxB KxB 20. Q-Q4 ch K-N1 21. N-N5 P-R3 22. N-K4 BxN 23. QxB N-R3 24. Q-K3 Q-B4 25. QxQ NxQ 26. KR-N1 KR-Q1 27. B-B1 R-Q3 28. R-N4 K-B1 29. P-QR4 R-R4 30. P-N3 K-K2 31. K-N2 P-B4 32. B-N5 R-Q7 33. R-Q4 (e) RxR 34. PxR NxP 35. RxN (f) RxB 36. R-R7 ch K-Q3 37. R-R7 P-R4 38. R-KN7 R-Q4 39. RxP P-N4 40. K-B3 P-N5 41. K-K3 P-N6 42. K-Q2 (g) RxP ch 43. K-B3 P-N7 44. KxP R-Q7 ch 45. K-B3 RxP 46. P-R4 P-B5 47. R-N5 R-B6 ch 48. K-Q4 RxP 49. RxP R-K6 50. R-R6 K-K2 51. P-R5 P-K4 ch 52. K-Q5 P-B6 53. Resigns

A. Pressuring the White center.

B. This concession, possibly unavoidable in the long run, should have been deferred.

C. The dissolution of the pawn center underlines the bankruptcy of White's strategy.

D. Now 18. NxB, QxN would spear the two Bishops and cost White two minor pieces for the Rook.

E. White cannot allow 33. . . . N-K5, which would tie him up completely.

F. 35. BxN, P-QN4 followed by 36. . . . PxB is no improvement for White.

G. 42. K-Q3, RxP ch transposes as 43. KxR, P-N7, allowing Black to Queen.