Thailand are looking forward to facing India in the third-place play-off at the King's Cup in Buri Ram on Saturday.
Thailand lost 1-0 to Vietnam in their opening match of the four-team tournament on Wednesday after goalkeeper Kawin Thamsatchanan failed to hold onto a soft header from Nguyen Anh Duc in the final moments.
Vietnam will play in Saturday's final against Curacao, who beat India 3-1 on Wednesday.
"I feel really disappointed that we lost," Thailand coach Sirisak Yodyardthai said after the match.
"We had several chances but could not score and were punished in the final seconds."
Kawin was picked ahead of Buriram United's Siwarak Tedsungnoen although he has been struggling for form at his Belgian club OH Leuven for some time.
Sirisak said he had discussed the matter with his assistants and decided to choose Kawin because Siwarak looked exhausted after playing several games in a row for his club.
Sirisak said he wanted to meet India again after they hammered Thailand 4-1 in their 2019 Asian Cup opener.
"I don't want to use the word 'revenge'. I only want to find out why we lost to them at the Asian Cup," he said.
Thanks to the result, Sirisak was named coach of Thailand.
Milovan Rajevac was in charge of the War Elephants for the match and was fired after the loss.
Vietnam coach Park Hang-Seo said: "I think it is great for Vietnam to beat hosts Thailand and reach the final. We worked very hard because it was a difficult game and my boys did it.
"The King's Cup is a great tournament. I think Thailand are Vietnam's No.1 rivals [in Southeast Asia]."
Vietnam, under South Korea's Park, have fared better than Thailand.
They won the 2018 Asean title and reached the quarter-finals at this year's Asian Cup.
