CHESS

The World Chess Challenge in Sofia, Bulgaria -- an eight-game match between U.S. grandmaster Gata Kamsky and the world's top-rated player, Veselin Topalov of Bulgaria -- is tied 2-2. After dropping the second game Wednesday, Kamsky evened the score on Saturday with a brilliant win in the fourth game, surprising Topalov with an astonishing pawn sacrifice in the Zaitsev variation of the Spanish opening. The match for the right to challenge the world champion, Vishy Anand of India, ends Saturday.

Kamsky-Topalov

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5 7.Bb3 d6 8.c3 0-0 9.h3 Bb7 10.d4 Re8 (The Zaitsev variation.) 11.Nbd2 Bf8 12.Ng5 Re7 13.d5 Nb8 14.Nf1 Nbd7 15.Ng3 g6 16.Bc2 (16.Be3 was played previously.) 16...h6 17.Nf3 Nb6 18.h4! Qd7 19.Nh2 (Avoiding 19.h5 Qg4.) 19...Bg7 20.h5! Rf8 21.Nhf1 c6!? (After Kamsky fixed the kingside with his h-pawn, black's only counterplay is in the center.) 22.dxc6 Qxc6 23.Ne3 Kh7 (It is too soon to break with 23...d5 because of 24.hxg6 fxg6 25.exd5 Nbxd5 26.Nxd5 Nxd5 and now either 27.Ne4 or 27.Be4 gives white a nice blockade of the important square e4.) 24.Qf3 Bc8 25.Rd1 Be6 (Kamsky finds an ingenious way to develop the queenside.)

26.b3! (A fascinating pawn sacrifice that black is almost obliged to accept because of the threat 27.Ba3.) 26...Qxc3 27.Bd2 Qc7 28.Ba5 Qb8 29.Rd2 Nc8?! (Too passive. Black should have played 29...Rc8 30.Rad1 Rd7.) 30.Rad1 (All white pieces are well placed. Black is tied up and has problems coordinating his forces.) 30...b4? (Concerned about 31.a3 and unable to stay put, Topalov makes a positional blunder, creating pawn targets on the queenside.) 31.Qe2 Kh8 (Avoiding 31...Rd7 32.Nef5.) 32.Bd3 Na7 33.Rc1! (Preventing 33...Nc6.) 33...Nb5 34.Bxb5 axb5 35.Bxb4 Rd7 36.Rc6 Rfd8 37.Qd1 Bf8 38.Qc2 Kh7 39.Ba5 Re8 40.hxg6+ fxg6 (The time control is over.)

41.Bc7! (Kamsky wins a pawn and ends up with a superior pawn structure and more active pieces.) 41...Qb7 42.Bxd6 Bf7 (After 42...Bc4 comes 43.Rc7! Rxc7 44.Bxc7 Qxc7 45.bxc4 with white's edge.) 43.Bb4 (Keeping the advantage, but the computer-like 43.Bxf8! is stronger, for example 43...Rxd2 44.Qc1! and after either 44...Nd7 45.Qxd2 Qxc6 46.Ng4! Kg8 47.Qxh6! Nxf8 48.Nh5 gxh5 49.Qxc6 hxg4 50.Qxb5; or after 44...Rxf8 45.Rxf6 Rfd8 46.Ngf1 R2d6 47.Nf5! gxf5 48.Qxh6+ Kg8 49.Rxd6 Rxd6 50.Qxd6 Qxe4 51.Qb8+ Kg7 52.Qxb5, white should win.) 43...Bxb4 44.Rxd7 Qxd7 45.Rxf6 Re6 46.Nd5 Bf8 47.Rf3! Kg7 48.Rc3 Ra6 49.Rc7 (The rook completes a full circle, doing the damage on the seventh rank.) 49...Qd6 50.Qe2 Kg8 51.Qxb5 Rxa2 52.Qb7 Ra1+ 53.Kh2 Bxd5? (Loses. The queen sacrifice 53...Qd8! 54.Ne7+ Bxe7 55.Rc8 Qxc8 56.Qxc8+ Bf8 offered the last chance to resist.)

54.exd5! (Threatening 55.Rc6 and 55.Ne4.) 54...Qf6 55.Qc8 Qh4+ (After 55...Qxf2 56.Qd7! Qg1+ 57.Kh3, white mates soon.) 56.Qh3 Qxh3+ 57.Kxh3 Rd1 58.Ne4! (White is winning.) 58...Ba3 (After 58...Rxd5? 59.Nf6+ Kh8 60.Rh7 mates.) 59.Ra7 Bb4 60.Rb7 Ba3 61.f3 Kf8 62.Rb5 h5 63.Kg3 Rc1 64.Rb8+ Kf7 65.Rb7+ Kf8 66.Kf2 Rc2+ 67.Kf1 Rc1+ 68.Ke2 Rc2+ 69.Kd3 Rxg2 70.Ra7 Be7 71.d6 Bd8 72.Nc5 Ke8 73.Rh7 (Good enough, but 73.Rg7, threatening 74.d7+ and 75.Ne6 mate, was stronger.) Black resigned.

Solution to today's three-mover by L. Kubbel (White: Kf1,Qa7,Rf2,P:a6,c5,d3,d6,e5; Black: Kd5,P:c6,d7,e6,g3): 1.Qa8! gxf2 2.Qd8! Kxc5 (or 2...Kxe5 3.Qg5 mate) 3.Qa5 mate; or 1...Kxc5 2.Rb2 Kd5 3.Rb5 mate; or 1...Kxe5 2.Qg8 Kd5 3.Rf5 mate.