Game 11 of the World Chess Championship last night was like a thunderstorm: brief, violent and lit up with flashes of brilliance that looked more threatening than they were. It ended in a draw (the ninth of the match) after only 24 moves and less than three hours of play. But it was a draw more interesting than many victories -- a game full of tactical finesses, mostly in its subtext, where analysts will be tracking them down for months.

Defending champion Gary Kasparov, who seized the initiative although he had the black pieces, had to settle for a draw -- indeed, to bully challenger Anatoly Karpov into one -- because, finally, he lacked the material to win. He had thrown away both his rooks in a whirlwind attack on Karpov's king, and a draw by perpetual check (shuttling his queen back and forth between squares h4 or h3 and g3) was his only way to avoid eventual disaster. Karpov, however, could not find any way to keep the game going and exploit his enormous material advantage.

First, Kasparov sacrificed the exchange, giving up a rook for a bishop, on Move 13. He had returned to his favorite King's Indian defense after running into problems with the Gruenfeld in Game 9, and he took only five minutes to make his first 14 moves, a clear sign that the opening was carefully prepared ahead of time. Karpov took approximately an hour to find his responses -- but he found the right ones.

Kasparov is the 13th official world champion; his birthday is April 13, and he considers 13 his lucky number. So it was probably no coincidence that this radical new idea in a familiar opening was sprung on the 13th move. Those who wonder why he didn't save it for Game 13 will wait with interest to see whether he has something even more violent for that occasion.

The exchange sacrifice was especially spectacular because it was not an immediate tactical choice; it was a positional sacrifice, allowing Kasparov to activate all his pieces while the white pieces lacked harmony. In exchange for the material inequality (which remained and grew through the rest of the game) Kasparov's king's bishop controlled the dark squares and within a few moves he was able to switch his queenside rook across the board to attack white's king.

His situation might have been even stronger if he had played 21. ... g5 with the idea of 22. ... Bd4 and 23. ... Qh6, but the way he played it was strong enough. Karpov was forced to find 22. g4, the only possible move to foil Kasparov's initiative.

With 23. Qxd4, Karpov accepted the peaceful solution to this dramatic game. With his enormous material advantage, the temptation to try to continue the game was great. But after an effort to do so, with 23. Qg2, Bxa1; 24. Rxa1, Qf6 followed by 25. Nf4, he might have risked going into a worse position.

The score is now 5 1/2-5 1/2, with one victory for each player. The first player to gain 12 1/2 points wins the championship and $1.7 million of the $3 million purse. If the match ends in a 12-12 tie, the purse will be split evenly and Kasparov will keep the championship he won in 1985.

Game 12 is scheduled to begin at 5:30 p.m. tomorrow, with Kasparov playing white. After that game, the match will move to Lyon, France, where Game 13 is scheduled for Nov. 24.

Lubomir Kavalek is a chess grandmaster. Joseph McLellan is a Washington Post staff writer.