Ratchayothin, who plays on the world professional circuit, first went down 5-2 to Ben Judge of Australia in the morning session at the Montien Riverside Hotel and then suffered another defeat at the hands of defending champion Mark Davis of England, losing 5-3 in the afternoon in his second Group A match.
With four players qualifying for the knockout stages from each group, Ratchayothin is now left with an uphill task of beating former world professional champion Ken Doherty of Republic of Ireland, seasoned Welsh professional Dominic Dale and reigning Asian champion Thor Chuan Leong of Malaysia to ensure a place in the last 32 round.
Veteran and former World No 3 Ratchapol Pu-Ob-Orm, better known as James Wattana, scored a hard fought 5-4 victory over European qualifier Alex Borg of Malta, but Noppon Saengkham, Kritsanut Lertsattayathorn, Thanawat Tirapongpaiboon and Boonyarit Kaettikun all lost their opening matches.
Jamie Clark from Wales defeated Kritsanut 5-3 and veteran professional and a former winner at the same event Jimmy White of England whipped the other Thai debutant Boonyarit, who finished runner-up at the Asian 6-red Championship last month, by the same scoreline.
Noppon was held scoreless in the deciding frame by Welsh professional Michael White who scored a narrow 5-4 victory, while Thanawat failed to match the wits of the Chinese wild card Liang Wenbo and lost his first group stage match 5-1.
As far as the host country is concerned, the scenario improved a bit with Thepchaiya Un-nooh and Dechawat Poomjaeng producing impressive results. Thepchaiya was 5-3 winner over Shivan Arora of India, while Dechawat routed Austrian qualifier Andreas Ploner 5-1.
Former world professional champion Shaun Murphy, world No 12 Stuart Bingham, No 15 ranked Joe Perry were victorious in their opening matches. Murphy, now ranked No 7, defeated Schachar Ruberg of Israel 5-2, Bingham beat Graeme Dott 5-2 and Perry was a 5-3 winner against Ahmed Galal of Egypt.
The Iranian players showed their prowess in the opening session with Hossein Vafaei Ayouri hammering Hung Chung Ming of Chinese Taipei 5-1 and Amir Sarkhosh whitewashing Arora 5-0.
Five sessions are scheduled to be played on the second day today at the same venue, starting at 10am.