HO CHI MINH City, Vietnam — Former Wold Cup campaigner GM Darwin Laylo defeated compatriot IM Richard Bitoon to keep a share of the lead with untitled Khoa Bao of Vietnam in the third round of the Asian Zone 3.3 chess championship at the First Hotel here.

Laylo, who is seeking his second straight World Cup appearance, parlayed a slim positional advantage into a rousing victory over Bitoon for his third straight win in this tough, nine-round tournament hosted by the Vietnamese Chess Federation.

Laylo will next meet Bao in the fourth round. Bao, one of 20 Vietnamese players entered here, pulled the rug from under GM Susanto Megaranto of Indonesia.

Top seed GM Wesley So whipped CM Nguyen Van y of Vietnam, while GM Mark Paragua battled second seed GM Zhang Zhong of Singapore to a draw to stay within striking distance with 2.5 points out of a possible three.

Joining So and Paragua are Zong, GM Nguyen Ngoc Truong Son of Vietnam and FM Timothy Chan of Singapore.

GM Eugene Torre settled for his second straight draw, this time against FM Tsegmed Batchuluun of Mongolia.