Coach Kiatisak Senamuang has refused to heed calls for him to field striker Adisak Kraisorn in Thailand's last match at the King's Cup tomorrow.
Adisak, who is the only striker in the Thai squad, has just returned from a shoulder injury and did not play in Thailand's first two games at the King's Cup.
Midfielder Chanathip 'Messi Jay' Songkrasin has started as a lone striker but has not yet scored in the four-team tournament in Nakhon Ratchsima.
Thailand beat Honduras 3-1 in the opening match and lost 5-2 to Uzbekistan on Wednesday.
They must beat South Korea by at least two goals in their final game tomorrow to stand any chance of lifting the trophy in the round-robin tournament.
There have been calls for Kiatisak to use Adisak but the coach said after the Uzbekistan match that his team's attack was good but defence was not.
"I won't use Adisak in the final match. Although he is now fit to play, we don't want him to get injured again as this will not be good for his club BEC Tero Sasana,'' he said.
"Our attack is good but our defence must be good too."
About the 5-2 loss to Uzbekistan, Kiatisak said: "We are Asean champions but the standard of Asian football is higher. Uzbekistan are at a higher level and played at the Asian Cup [last month]."
Uzbekistan at the King's Cup are a U22 side with a couple of full international players.
Reigning Asean champions Thailand failed to reach the 2015 Asian Cup finals.