Although he remained too far behind Wiratchant, who had a 13-under 203, Pucay, who started the round in 44th place, put himself in a position for a top 10 finish with a 210.
Wiratchant wrested a one-stroke lead over halfway round leader Scott Kammann of the US, who carded a 70 for a share of second with Chinese Zhang Lian-wei, who had a 68.
Danny Zarate, the erstwhile best-placed Filipino shotmaker, shot a 71 as he slid to 33rd.
Over in Ohio, Dorothy Delasin fired an eagle-aided 70 to trail Leta Lindley (64) by six strokes in the $1 million New Albany Classic.