Leaders after five rounds(RP, unless stated): 4.5 points—S. Megaranto (Indonesia), W. Zhou (China); 4—R. Antonio, J. Sadorra, R. Nolte, E. Maghami (Iran), Q.L. Le (Vietnam), C. Li (China); 3.5—W. So, D. Ballecer, Z. H. Wynn (Myanmar), H. Jia (China), M. Mahjoob (Iran), D. Liu (Indonesia), J. Zhang (China)

SUBIC -- FILIPINO SENSATION WESLEY So’s unbeaten run finally ended Saturday.

Rising Chinese star Weiqi Zhou handed So a rare loss in the fifth round of the 2008 Philippine Open International chess championship to keep his share of the lead with Indonesian Grandmaster Susanto Megaranto at the Subic Bay Exhibition and Convention Center.

Zhou, co-champion in the A2 section of the tough Aeroflot Open in Russia, last month, adeptly handled black in stunning So after 32 moves of the French defense to raise his total to 4.5 points.

The 14-year-old So could have avoided his first loss in more than a month as Zhou offered a draw after 18 moves. So rejected it but later made a weak Qf4 move that allowed the untitled but highly rated Zhou (Elo 2560) to gain control with a lethal queen, rook, bishop attack.

“I should have moved Qf6 and the game would still be a draw,” said So, who last tasted defeat at the hands of Megaranto in their one-on-one showdown in Jakarta, Indonesia, in April.

Megaranto, who yielded to So in that duel (4-2), bested erstwhile solo leader GM Li Chao of China in 24 moves of the Sicilian Nadjorf to keep pace with Zhou in the 11-round -tournament organized by the National Chess federation of the Philippines and supported by the Department of Tourism and the Subic Bay Metropolitan Authority.

GM Rogelio Antonio Jr. rebounded from a fourth-round setback to Li by downing National Master Emmanuel Senador to move up to 4.0 points in the company of IM Julio Catalino Sadorra, NM Rolando Nolte, top seed GM Ehsan Ghaem Maghami of Iran, GM Le Quang Liem of Vietnam and Li.

The Singapore-based Sadorra trounced WIM Xiaowen Zhang of China, Nolte beat GM Nguyen Anh Dung of Vietnam, Maghami downed IM Tirta Purnama of Indonesia and Le whipped IM Barlo Nadera.

Unheralded Dino Ballecer shocked Malaysian IM Hafizulhelmi Mas to join So and five other foreigners with 3.5 points going into the sixth round late Saturday.

In the same group were GM Mahjoob Morteza of Iran, IM Zaw Htun Wynn of Myanmar, IM Dede Liu of Indonesia and untitled Haoxiang Jia of China,

The 21-year-old Zhou, a two-time member of the Chinese team in the World Under-16 Olympiad in 2000 and 2002, seized the momentum after So made a pawn push on the 18th move and was threatening mate in two moves when the Dubai Open champion resigned.

So, who was unscathed in ruling the recent Battle of GMs, won his first three matches against FM Roderick Nava, IM Tirta Purnama of Indonesia and Reggie Olay before drawing with Li in the fourth round late Friday.

World age-group campaigner Karl Victor Ochoa stunned IM Aung Aung of Myanmar to rise to 2.0 points.