World junior champion Pendyala Harikrishna's good form continued as he outsmarted Grandmaster Zhang Zhong of China in the fourth round of the Sanjin Hotel Cup Grandmasters' chess tournament in Taiyuan, China, on Tuesday.

With his fourth victory on the trot, Harikrishna continues to lead the table with four points. Following him a half point behind is Grandmaster Tigran Petrosian of Armenia, who scored his third victory in the event, accounting for English GM Luke McShane.

Former Russian champion Alexander Motylev and the Chinese duo of Wang Yue and Bu Xiangzhi are next in line on 2.5 points apiece, but holding the edge here is the Russian as he still has an extra game in hand against Chinese GM Ni Hua that will be played on the rest day.

With seven rounds still remaining in the category 15 round-robin event Wang Hao of China stands sixth on 2 points. Trailing him are McShane and Ukrainian GM Sergey Karjakin.

The fourth round yet again produced as many as five decisive games with a change of guard as white pieces took the front seat with 4.5-1.5 score compared to 0.5-5.5 in the previous round.

Harikrishna once again showcased his endgame prowess, bruising and eventually squeezing out the defenses of Zhong, the Corus 'B' champion of 2004.

The opening featured the Leningrad Dutch where the Chinese played black and steadily Harikrishna got a slight advantage in the middle game.

As the game progressed, it was evident that black had some counter play and Zhong found some solace after losing a pawn that led to a seemingly drawish endgame with regular exchange of pieces.

However, Harikrishna's ability to just continue in the queen and pawn endgame was something that Zhong was not aware of. Playing very important intermittent moves between some puzzling manoeuvres, the Indian simply bewildered his rival.

When the dust eventually settled, Harikrishna obtained a central passed pawn and slowly increased his advantage by marching the king in to heart of black's position.

The marathon ended after 109 moves, by far the highest in the tournament, giving Harikrishna immense satisfaction.

For Petrosian too, it was a very satisfying day with McShane falling out to some deft planning. The King's Indian defense did not come good against a Russian-speaking player for the umpteenth time as Petrosian, white, simply made his queen superior to black's double rook in the middle game.

Knocking down a couple of pawns, the Armenian finally won a piece to force matters in 59 moves.

For the second day running, Motylev recorded a smooth victory in a King and pawn endgame. On the receiving end was former World Junior girls' champion Zhao Xue of China, who had little clues once again as to what hit her.

The Russian first won a pawn in the Rue Lopez, exchanged queens quickly and finally liquidated to a winning endgame to romp home in just 37 moves.

In other games of the day, Wang Yue defeated Wang Hao in a keenly-fought endgame, while the world's youngest ever Grandmaster, Sergey Karjakin of Ukraine, registered his first victory in the event, accounting for Ni Hua of China.

The lone draw of the day was between Chinese Bu Xiangzhi and Zhang Pengxiang.

Results, round 4: P Harikrishna (Ind, 4) beat Zhang Zhong (Chn, 1); Tigran Petrosian (Arm, 3.5) beat Luke McShane (Eng, 1.5); Alexander Motylev (Rus, 2.5/3) beat Zhao Xue (Chn, 0); Wang Yue (Chn, 2.5) beat Wang Hao (Chn, 2); Ni Hua (Chn, 1/3) lost to Sergey karjakin (Ukr, 1.5); Bu Xiangzhi (Chn, 2.5) drew with Zhang Pengxiang (Chn, 1).

The moves:

P Harikrishna v/s Zhang Zhong

d4 f5 2. g3 Nf6 3. Bg2 g6 4. Nf3 Bg7 5. O-O O-O 6. b3 d6 7. Bb2 Qe8 8. c4 e5 9. dxe5 Ng4 10. Qd2 Nxe5 11. Nc3 Nbc6 12. Nd5 Qd8 13. Rad1 Bd7 14. Nxe5 Bxe5 15. c5 Be6 16. Nf4 Bf7 17. cxd6 cxd6 18. Ba3 Qb6 19. Nd5 Qd8 20. Nb4 Qb6 21. Nxc6 bxc6 22. Qc2 Rad8 23. Qxc6 Qa5 24. Bxd6 Bxd6 25. Rxd6 Rxd6 26. Qxd6 Qxa2 27. Bf3 a5 28. Qe5 Re8 29. Qc3 Qxb3 30. Qxa5 Rc8 31. Ra1 Qb2 32. Kg2 Qd4 33. Rb1 h5. 34. h4 Rd8 35. Rb7 Qf6 36. Qc7 Rd6 37. Rb8+ Kg7 38. Qc8 Kh7 39. Rb7 Kg7 40. Qc5 Kg8 41. Ra7 Qd4 42. Qc7 Qf6 43. Ra8+ Kg7 44. Rb8 Qe6 45. Qb7 Qf6 46. Ra8 Rd8 47. Ra7 Kg8 48. Ra6 Qe5 49. Qb6 Rd7 50. Ra5 Q d4 51. Qb8+ Kh7 52. Qb5 Ra7 53. Rxa7 Qxa7 54. Bd5 Bxd5+ 55. Qxd5 Qe7 56. Kf3 Qb4 57. Qe5 Qg4+ 58. Ke3 Qc4 59. Qd4 Qc1+ 60. Kf3 Qc7 61. Qd5 Qb8 62. Kg2 Qc7 63. f3 Qc2 64. Kf2 Qb2 65. Qc4 Qb6+ 66. Kg2 Qb2 67. Qf7+ Kh6 68. Qe7 Qa2 69. Qe3+ Kh7 70. Qf2 Qa4 71. Qe1 Qc2 72. Kf2 Qb2 73. Qd1 Qa2 74. Qd7+ K h6 75. Qd6 Kh7 76. g4 hxg4 77. fxg4 fxg4 78. Qd7+ Kh6 79. Qxg4 Qd2 80. Qf3 Qd4+ 81. Kg3 Qg1+ 82. Kh3 Kg7 83. e3 Qe1 84.Kg4 Qg1+ 85. Kf4 Qh2+ 86. Qg3 Qd2 87. Qg5 Qh2+ 88. Kf3 Qh1+ 89. Ke2 Qh2+ 90.Kd3 Qd6+ 91. Ke4 Qc6+ 92. Kf4 Qc1 93. Qe5+ Kh7 94. Kg5 Qg1+ 95. Kf6 Qf2+ 96.Qf4 Qb2+ 97. Qd4 Qf2+ 98. Ke 7 Qh2 99. Qf4 Qd2 100. Ke8 Qc1 101. Kf7 Qd2 102.Qe4 Qf2+ 103. Ke8 Qh2 104. Qe7+ Kh6 105. Qg5+ Kg7 106. e4 Qc2 107. Qe7+ Kh6 108. e5Qc8+ 109. Kf7 Qc4+ 110. e6 black resigned.

• Complete chess coverage