Thailand failed to make it to the AFF U19 Boys Championship final after a shock 2-0 defeat at the hands of Laos at the Patriot Stadium in Jakarta on Wednesday night.
Laos have reached the final of the tournament for the first time since its inception in 2002, with their best finish being finishing third in the 2002, 2005 and 2015 events.
"It was beautiful. Since I have been here for six months, we try to do something. The best is yet to come. We did not play really good football in most games but we were solid, with good structure. With this kind of football, we can win games," said Laos head coach Michael Weiss after the match.
With five-time winners Thailand the overwhelming favourites considering their track record, it came as no surprise that they started to stamp their dominance early in the game.
But Laos, who had maintained a perfect winning record in the group stage, looked determined against their fancied opponents as they defended hard before scoring a goal in each half for the win.
It took Laos just eight minutes to get onto the scoresheet when Peeter Phanthavong stabbed home the corner from Sayfon Keohanam to give them a well-deserved lead.
The rattled Thai squad pushed hard in search of the equaliser but neither Phanthamit Praphanth nor Nattakit Butsing could take their chances.
The substitution for an added attacking option in the second half didn't work as well as Laos continued to defend hard.
Thailand lacked cohesion and it was Laos who made sure of their place in the final when a quick counter-attack in the 85th minute saw Damoth Thongkhamsavath run down the right and unleash a stiff grounder to beat Thai custodian Narongsak Naengwongsa for the second time on the night.
Thailand U19 head coach Salvador Garcia said after the loss: "They got two chances and they scored two goals. We had seven or eight chances but we did not score. That is part of football. I tried to change the formation to be more offensive. But when you don't have the day, you don't have the day."
In the other semi-final match, Malaysia defeated Vietnam 3-0.
Thailand will next face Vietnam in the third-place play-off on Friday while Laos will take on Malaysia in the final later on the same day.