Manotoc, a manytime low medalist of the RP Open, went out with a 38 before coming home with a 39 to lead fellow amateurs Solomon Gines (78) and Jun Bernis (78) going to todays final 18 holes.
Lyndon Barril, another amateur, was at 80 after a fat 42 coming home and then Japanese Toyoda Kunihiro was the best-placed pro at 81 in a tie with Ronnie Torrecampo, another amateur.
Dave Hernandez had a front-nine 38 but struggled coming home with a 44 for 82, the same output of Bernard Villa and Korean Seong Ki Lee.
The top 10 finishers after today will advance to the Philippine Open on March 7-10 at Wack Wack.
A Pro-Am on March 6 will precede the tournament bankrolled principally by Pagcor through Casino Filipino and main presentor San Miguel Beer.
Mitsubishi is the official car of the event, now a part of the Davidoff Tour of the Asian PGA.