Zarate, who started the round bunched in 15th place with compatriots Gerald Rosales, Rodrigo Cuello and Danny delos Santos, gunned down six birdies in another day of torrid scoring although his bid was stymied by three bogeys, including one on the par-5 No. 4, which he eagled in the first round.
Still, Zarate’s 36-hole aggregate of 138 put him among the frontrunners in the event, which serves as the second to last in this year’s Asian PGA Tour calendar.
Buhrmann, runner-up in this event two years ago, surged to a three-stroke lead over American Ahmad Bateman and two others with a second 66 for a 132.
Mars Pucay, who started the day in 61st position, jumped to a share of 17th with a fiery 67 to join De los Santos, who had a 70, at 139, one stroke ahead of Rosales, the RP Open champion who carded a 71 after a 69, while Cuello slid to 33rd place at 141 after a 72.