The up-and-coming Thai star has delighted home fans sharing the clubhouse lead at the end of each of the first two days.
Six birdies during Saturday's third round -- including a pair on the final two holes -- took him to 17-under for the tournament (196).
That gave him a one-shot lead over compatriot Panuphol Pittayarat, 24, who scorched round the Thai Country Club in 64 and has dropped only one shot so far this week.
Indian ace Gaganjeet Bhullar remained within striking distance on 15-under, with another Thai favourite -- Kiradech Aphibarnrat -- a shot further back after notching a 65.
Only three Thais have won the Thailand Open since 1965.
Leading scores after round two of the $300,000 Asian Tour Thailand Open at the Thai Country Club on Friday:
196 - Rattanon Wannasrichan (THA) 62-69-65
197 - Panuphol Pittayarat (THA) 64-69-64
198 - Gaganjeet Bhullar (IND) 65-66-67
199 - Kiradech Aphibarnrat (THA) 66-68-65
200 - Ben Leong (MAS) 70-64-66, Terry Pilkadaris (AUS) 67-67-66, Pawin Ingkhapradit (THA) 70-62-68,
201 - Scott Barr (AUS) 67-67-67
202 - Suradit Yongcharoenchai (THA) 71-67-64, Shiv Kapoor (IND) 70-67-65
