Thailand coach Worrawoot Srimaka said his men lacked courage in their 1-1 draw with hosts Mongolia in their opening Group J game of the AFC U23 Championship qualifiers on Monday.
Thailand went in front after just 10 minutes when Thanawat Suengchitthawon's weighted cross into the area found Jakkit Palapon, who scored with a volley past Mongolia goalkeeper Sereekhuu Batmagnai.
However, a second-half resurgence from Mongolia saw them draw level 15 minutes from the end courtesy of Batbold Baljinnyam's goal.
Thailand goalkeeper Kiattipon Udom's poor clearance was intercepted by Baljinnyam, who finished with a fine strike.
It was an unfortunate blunder by Kiattipon, who had thwarted Mongolia on several occasions before conceding the goal.
The Thais not only failed to win but also missed out on a lucrative bonus from team manager Nualphan Lamsam who has promised to give them one million baht for each win.
"Our players played quite okay, but we conceded the goal from our mistake. Also, we must be more courageous," said Worrawoot.
"We would like to apologise to Thai fans for not being able to get three points. However, in the next two matches, we must reduce our mistakes and try to get all six points to secure a place in the finals."
During Monday's game, Thailand were dealt blows when Benjamin Davis and Wanchart Choosong were injured and replaced by Sittha Boonlah and Antonio Sangjairak in the first half.
"Wanchart should be able to play in the next two games while Benjamin may not be available for the next game against Laos. Both got injured probably because of the pitch," said Worrawoot.
In other Group J game, Malaysia defeated Laos 1-0.
Thailand next meet Laos on Thursday when Mongolia face Malaysia.
The 11 group winners plus four best runners-up will join Uzbekistan in the finals in June next year.