FIDE Masters Ildefonso Datu and Fernie Donguines also shared opening day honors over their foreing rivals. Datu turned back International Master Benny Juswanto of Indonesia in 54 moves of an English Opening while Donguines trounced Hasnul Bin Hasim of Brunei in 35 moves of a Reti-Opening in this nine-round event.
Dao, who topped last years Zonals with Filipino GM Buenaventura Villamayor in Vietnam, beat Cedep Koszih of Indonesia in 41 moves while Nguyen scuttled top local IM Chito Garma in 50 moves of a Queens Gambit-Declined.
Adianto and Handoko likewise hurdled their first round assignments with the former turning a drawish position into a resounding triumph over FM Yves Rañola (55-Caro-Kann) and Handoko whipping Chor Yvezn Cheng of Hong Kong (13-Sicilian).
Three of the top six local chessers, GMs Eugene Torre and Villamayor and IM Mark Paragua, settled for draws.
Torre, who won the recently-concluded National Open, halved the point with NM Darwin Laylo (47-Torre Attack), Villamayor split the point with NM Emmanuel Senador (28-French), and Paragua agreed to a 40-move standoff with NM Allan Sayson (Kings Indian Attack).
In womens play, WIM Beverly Mendoza posted RPs lone win, beating Hong Kongs Li Ching in 31 moves of a Caro-Kann.