The draw as black came easy in the return game and Ivanchuk completed a 1.5-0.5 victory over Anand in the two games played. It may be recalled that the Ukrainian had beaten Anand in the third round which was held at Sao Paulo in Brazil.
Meanwhile, World number one Magnus Carlsen of Norway and Hikaru Nakamura of United States closed in on the leader with fine victories in the eighth round games.
Magnus played determinedly to beat Francisco Vallejo Pons of Spain, Nakamura showcased his endgame skills to beat Levon Aronian of Armenia.
Ahead of the final rest day, Ivanchuk remained in sole lead on 14 points in the soccer-like scoring system while Nakamura and Carlsen are now two points behind the leader.
With just two rounds to come, Anand slipped to the fourth on nine points, a half point ahead of Aronian. Pons remains at the bottom of the tables on seven points.
Anand employed the Queen's Indian defense to counter Ivanchuk's queen pawn opening. The Ukrainian managed to get some complications on board in the middle game but after the center was opened Anand exchanged pieces at will to reach a level knights and pawns endgame.
In the end, both the players had two passed pawns and making progress was not possible. The game was drawn in 58 moves.
Carlsen faced the Slav defense against Pons who played black. The Spaniard equalised early in the opening but fell prey to some wily manoeuvres after the queens got traded. Carlsen won a piece for two pawns and the resulting endgame was child's play.
Nakamura was at his best in the Queen's gambit declined employed by Aronian. The American got a slightly better middle game and squeezed out black's defensive resources to reach a better endgame.
Aronian tried hard to make a match for it but an erroneous plan led to the demise of his minor piece in the endgame and Nakamura wrapped the issue in 79 moves.
Results round 8:
Vassily Ivanchuk (Ukr, 14) drew with V Anand (Ind, 9); Hikaru Nakamura (Usa, 11) beat Levon Aronian (Arm, 8); Magnus Carlsen (Nor, 11) beat Francisco Vallejo Pons (Esp).
The moves. V Ivanchul v/s V Anand 1. d4 Nf6 2. c4 e6 3. Nf3 b6 4. Nc3 Bb7 5. Bg5 h6 6. Bh4 Be7 7. Qc2 c5 8. dxc5 bxc5 9. e3 O-O 10. Be2 d6 11. O-O Nbd7 12. Rfd1 Qb6 13. Rd2 Rfd8 14. Rad1 a6 15. h3 Bc6 16. Ne1 Qc7 17. Bf3 Ne5 18. Bxc6 Qxc6 19. b3 Ra7 20. Bg3 Qc8 21. Na4 Re8 22. Bh4 Ned7 23. Nc3 Ra8 24. f4 Qc7 25. Nf3 Rad8 26. e4 Nb8 27. e5 dxe5 28. fxe5 Rxd2 29. Qxd2 Rd8 30. Qe1 Rxd1 31. Nxd1 Nh7 32. Bxe7 Qxe7 33. Nf2 Qc7 34. Ne4 Nf8 35. h4 Nbd7 36. Nf2 Ng6 37. Nd3 Ne7 38. Qe4 Qc6 39. Nf2 Qxe4 40. Nxe4 Nc6 41. Kf2 Kf8 42. g4 Ke7 43. g5 a5 44. Ke3 Ncxe5 45. Nxe5 Nxe5 46. Nxc5 hxg5 47. hxg5 f5 48. gxf6+ gxf6 49. a3 f5 50. Kd4 Nc6+ 51. Kc3 Kd6 52. b4 axb4+ 53. axb4 e5 54. Nb3 e4 55. b5 Nd8 56. c5+ Kd5 57. Nd4 Kxc5 58. Nxf5 Nb7 game drawn.