Namchok Tantipokhakul took full advantage of playing on his home course on Friday with a 69 to take a two-shot lead into the final round of the B-ing Championship on the Mercedes-Benz Tour.
The 22-year-old Thai is on seven-under-par 209 at Bangpra Golf Club.
Countryman Chawinroj Rungsrichai, looking for his first win after five years as a professional, shot a sizzling four-under 68 to grab second spot.
He lies three shots ahead of 18-year-old pro debutant Phiphatphong Naewsuk, who carded a 70 for third place.
A frustrated Prayad Marksaeng, the world number 85 who has not been able to buy a putt all week, returned a one-over 73 and is six off the pace in tied fourth with fellow Thais Sattaya Sapupramai and Udorn Duangdecha.
Namchok practices regularly at Bangra Golf Club and knows the nuances of the tricky greens, putting it to good effect on Friday.
"I know everything about the greens here which is a huge help," said Namchok.
"I have been second before on the Mercedes-Benz Tour and I am confident I can win on Saturday.
"There will be less pressure on me as Prayad will not be in the final group and I plan just to play steady and continue to hit fairways and greens."
Thailand unless stated:
209 - Namchok Tantipokhakul 73-67-69
211 - Chawinroj Rungsrichai 72-71-68
214 - Phiphatphong Naewsuk 76-68-70
215 - Prayad Marksaeng 72-70-73, Udorn Duangdecha 70-72-73, Sattaya Sapupramai 71-70-74
216 - Nadeem Inayat (PAK) 72-74-70, Atthaphon Prathummanee 69-71-76
217 - Antonio Lascuna (PHI) 71-73-73, Baek Seuk-hyun (KOR) 74-70-73, Gene Bondoc (PHI) 73-69-75, Panuwat Muenlek 72-73-72
218 - Somchai Pongpaew 71-77-70, Chan Song Wongluekiet 76-71-71, Thammanoon Srirot 70-72-76