Game 21 of the World Chess Championship ended in a draw yesterday in Lyon, France, after 86 moves, which took 9 hours 20 minutes to play, spread over two days. The draw, the 15th in the match, leaves the score at 11 1/2 to 9 1/2 in favor of defending champion Gary Kasparov.

There are a maximum of three more games in the match, which is limited to 24 games but could be shorter. It will end if either player reaches 12 1/2 points; Kasparov can do this by winning one more game or drawing two; Karpov must win all three remaining games to regain the title he lost to Kasparov in 1985. Kasparov will keep his title if the match ends in a 12-12 draw, and the $3 million prize fund would be divided evenly. If there is a clear winner, the first prize will be $1.7 million, so the final game may be worth $200,000 and certainly will be played if there is any possibility that it will matter.

Karpov's Move 41, b5, which had been written down and kept overnight in a sealed envelope, took the sting out of Kasparov's threatened attack. The pawn, occupying a key white diagonal, cut off any possible aggressive approach by Kasparov's queen toward Karpov's king.

Both players moved quickly in the early phases of the second session, indicating that the position had been thoroughly analyzed overnight and all the possibilities weighed. Karpov's sacrifice of the exchange (rook for bishop) on Move 43, for example, must have been the result of overnight analysis.

After the exchange of queens on Move 45, Kasparov was happy to repeat moves and make a draw, but Karpov made a last-minute attempt to win with 51. b4. Kasparov countered this effectively; first, he sacrificed a knight for the dangerous b-pawn; then he was able to knock the h-pawn off the board, clearing the way for his own h-pawn to run down and become a queen. In the pawn race that ensued, Kasparov's timely sacrificial stroke on Move 57 (echoing Karpov's earlier exchange of rook for bishop) won his pawn the chance to reach the finish line one move ahead of Karpov's b-pawn.

With queens back on the board, the only way Karpov could continue was to give up his last pawn, but then his small material advantage was only theoretical. The players could have agreed to a draw 20 moves before they actually did.

The players stayed onstage for about 45 minutes after the game, analyzing various possibilities. "They are talking so much now because they both feel the match is basically over," U.S. grandmaster (and Soviet emigre) Lev Alburt told a Reuter reporter.

Game 22 is scheduled for tomorrow, with Kasparov playing white.

Kavalek is an international grandmaster; McLellan is a Washington Post staff writer.

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