The fight is on again in Moscow after a quiet week in the world chess championship match. Champion Anatoly Karpov and challenger Gary Kasparov battled to a 31-move draw in the seventh game Saturday, but this draw was a real struggle, unlike the uneventful sixth game. Karpov has won two games, Kasparov one, and the match score stands at 4-3 in Karpov's favor.

With Kasparov playing white, the game began as an echo of the first game of the match, which had ended in a disaster for Karpov. After Kasparov repeated the same fourth move he had made in Game 1, Karpov changed his tactics, castled and went into a very conservative defensive position for a half-dozen moves.

Karpov was lured out of his shell in the middle game, in response to Kasparov's flamboyant tactics (which show the challenger returning to his old form), and then demonstrated that he can hold his own and even grab an advantage in Kasparov-style toe-to-toe slugging.

Kasparov's sacrifice of the exchange on his final move was virtually forced; with a queen, bishop and rook all poised to pounce along open lines, Karpov had the elements of an overwhelming attack. But with the tempo and open lines created by the inevitable recapture (. . . exd5), Kasparov had the option of forcing a draw by perpetual check. There could have been some tricky play remaining, if Karpov had chosen a line like 31 . . . Qa3ch; 32. Kb1, exd5. Kasparov then would have regained the initiative, but even with an advanced passed pawn, he would have had to keep up a constant series of checks (possibly 33. Qf6ch, Kg8; 34. Qd8 ch, Kg7; 35. Qf6ch, Kg8; etc.) to ward off Karpov's threatened checkmate ( . . . Rh1ch).

A Nizmo-Indian defense was used in Saturday's game:

White/Black Kasparov/Karpov

1. d4Nf6 2. c4e6 3. Nc3Bb4 4. Nf30-0 5. Bg5d6 6. e3Nbd7 7. Qc2b6 8. Bd3Bxc3ch 9. bxc3h6 10. Bh4Bb7 11. Nd2g5 12. Bg3Nh5 13. Qd1Ng7 14. h4f5 15. hxg5hxg5 16. f3Qe7 17. Qb3Kf7 18. 0-0-0Rh8 19. c5dxc5 20. Nc4cxd4 21. cxd4f4 22. Bf2Nh5 23. Bc2fxe3 24. Bxe3Bd5 25. Qd3Rag8 26. Ne5chNxe5 27. dxe5Nf4 28. Bxf4gxf4 29. Rxh8Rxh8 30. Qg6chKf8 31. Rxd5Drawn