Viswanathan Anand continued to share the lead with three other players after six rounds in the 66th Corus Grandmasters Chess tournament at the De Moriaan Centre. All four winners, Anand, Vladimir Kramnik, Michael Adams and Veselin Topalov played with white pieces.

Anand beat his bunny Alexey Shirov with Indian pieces, even as the Latvian-born Spaniard Shirov went into he usually dour Petroff defence. Anand, who has held a psychological whiplash over Shirov ever since he crushed him in the the FIDE World Championships final in Teheran in 2000, took 56 moves for the full point. Anand now has four points from two wins and four draws.

In other matches, Veselin Topalov beat Viorel Bologan in 52 moves of a closed Ruy Lopez, while Michael Adams outplayed Evegeny Bareev in a 25-move French Tarrasch and Vladimir Kramnik dealt newcomer Chinese player, Zhang Zhong in a longish 78-move game from an English opening. The other three games, Leko-Akopian, Sokolov-Van Wely, Timman-Svidler ended in draws.

Amongst the draws, the 52-year-old Jan Timman held fourth seed Russian champion Peter Svidler to a draw in a surprise result.

The Anand-Shirov game was fairly routine in the beginning in the tried and tested lines of the Petroff defence. By the 24th move, the two players had exchanged most of the pieces and had left a rook and knight each. Anand won a couple of pawns and then ensured the exchange of knights to reach an ending where he had two pawns and a rook against Shirov's rook.

This position has in the past seen draws, but Anand piled on the pressure and forced a mistake out of Shirov. With Anand's pawn getting to the seventh rank, Shirov's rook which was trying to stop it was distanced from his king and that resulted in his resignation on the 56th turn.

Anand admitted he may have missed a winning move earlier, but then said, "I may have missed a winning move but did not lose any opportunity to apply fresh pressure. I knew I had the win."

Pairings for Round 7: Akopian v Adams; Van Wely v Leko; Bologan v Sokolov; Svidler v Topalov; Shirov v Timman; Zhong v Anand; Bareev v Kramnik.

Results of Round 6: Topalov beat Bologan; Anand beat Shirov; Adams beat Bareev; Leko drew with Akopian; Kramnik beat Zhang; Sokolov, drew with Van Wely; Timman drew with Svidler.

Standings after Round 6: Anand, Topalov, Adams and Kramnik 4.0 each; 5. Leko 3.5; 6. Akopian, Van Wely and Svidler 3.0 each; 9. Sokolov, Timman and Bareev 2.5 each; 12. Shirov, Bologan and Zhang 2.0 each.

Anand v Shirov
Round 6, Wijk Aan Zee
Petroff defence

1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 6. Bd3 Bd6 7. O-O O-O 8. Re1 Bf5 9. c4 c6 10. cxd5 cxd5 11. Nc3 Nxc3 12. bxc3 Bxd3 13. Qxd3 Nd7 14. Qf5 Nb6 15. Ng5 g6 16. Qh3 h5 17. g4 Qd7 18. gxh5 Qxh3 19. Nxh3 Rfe8 20. Bf4 Bxf4 21. Nxf4 g5 22. Nh3 Na4 23. Rac1 Rxe1+ 24. Rxe1 Nxc3 25. Re7 Kg7 26. Rc7 Ne2+ 27. Kf1 Nxd4 28. Nxg5 Kh6 29. Nxf7+ Kxh5 30. Rxb7 Nf3 31. Rb5 Kg6 32. Rxd5 Nxh2+ 33. Kg2 Kxf7 34. Kxh2 Ke6 35. Ra5 Kd6 36. f4 Rg8 37. f5 Ke7 38. Rxa7+ Kf6 39. Ra5 Rg4 40. a4 Rb4 41. Kg3 Rc4 42. Kf3 Rh4 43. Ke3 Rg4 44. Kd3 Rf4 45. Ra8 Kg7 46. Ra7+ Kf6 47. Ra5 Rh4 48. Kc3 Rf4 49. Kd3 Rh4 50. Ra8 Kxf5 51. a5 Kg6 52. a6 Kg7 53. Ra7+ Kf6 54. Kc3 Re4 55. Rh7 Ra4 56. a7 White wins