Manalo and Guevarra rallied from 0-1 and 2-1 deficits in the finals to extend the match to a deciding fifth frame, but the Thais raced to an early lead and never looked back on the way to wrapping up the gold medal.
"Medyo nag-kulang. Twice pang nag-foul si Benjie sa fifth rack. Malaking bagay yon," said coach Ricardo Ancaja of the RPs bid, which ended in a silver.
In a performance that began early morning and ended late in the evening, the Filipinos won their first two matchups in contrasting fashion to earn their ticket to the championship.
Manalo, runnerup in the recent world snooker tourney held in Akita, Japan, and Guevarra rallied past Sang Chong Amn and Ng Ann Seng, 3-2, in their opening match.
They won the second and third racks to take a 2-1 lead in the best-of-five series but allowed their foes to come back after losing the fourth frame 17-76.
Manalo, who won the doubles gold with Joven Alba in the 1995 Chiang Mai SEA Games, held the team together in the rubber match which the Filipinos won, 65-45.
In the second round actually the semifinals in the seven-team field the RP duo dropped the first frame but secured the next three for a 3-1 triumph over the Indon pair of Sayuming Teng and Teng Khee Shien to advance to the finals.
The Thais drew an opening-round bye then crushed the Bruneis Randy Wong Siew Loong and Saharj Haji Emran, 3-0, in the semis to set up a title showdown with the Filipinos.