Game 20 of the world chess championship ended in a draw yesterday, leaving at least two questions without a clear answer.

One, of course, was the question of who should be the world chess champion. But besides that a sort of sub-question has risen, like a side bet at a roulette table, between champion Gary Kasparov and challenger Anatoly Karpov in the last few games: Who is the best player of the Queen's Gambit?

You might think that in this ancient opening, which has been part of the world championship repertoire since the last century, not many new ideas can be produced. But strangely enough, one very new idea that has been popularized during the last three years was used in Game 20 by Kasparov.

Karpov was able to handle it without difficulty, however, and the match score remains tied, at 10-10. Kasparov will keep his title if the 24-game match is tied at 12-12. With four games remaining, Karpov has to win at least one to take back the title he lost to Kasparov two years ago.

Kasparov began exploring the new idea with the move 5. Qc2, and in the next eight moves he managed to gain a spatial advantage. But, as usual in the black side of a well-played Queen's Gambit, Karpov's position remained very solid. He had no pawn weaknesses, and he was able to weather any attacking ideas Kasparov might have had.

Still, while Karpov never ran into serious problems, Kasparov's position after 23 moves remained more pleasant. Karpov defended well, however, placing his queenside pawns on black squares where they could not be touched by Kasparov's bishop.

Eventually, it became clear that there was no way Kasparov could make progress. In the final position, he had an opportunity to continue the fight -- by taking the pawn on e6, for example -- but shifting into that sort of hostility would have given Karpov some dangerous opportunities.

While he could not generate a winning attack, Kasparov was clearly able to paralyze Karpov with a perpetual check -- repeatedly using his queen to attack Karpov's king, which was restricted to the seventh and eighth ranks. But while Kasparov could harass the king, he could not mate it. So a draw became the only possible outcome.

Karpov will have white in Game 21, which is scheduled to begin on Monday. And with the opportunities to take the lead slowly shrinking away, he may decide to come out swinging.

zrandmaster Lubomir Kavalek contributed to this report.