Thailand coach Mano Polking said on Wednesday although Indonesia are strong, his men are capable of getting past them for a place in the men's football final on Thursday.
In today's other semi-final, holders Vietnam take on Malaysia.
"The Indonesian players have played together for a long time. They understand each other and play with an aggressive style. They have a good attacking game with a good system and good plans," Polking told a press conference.
"Some of their players have already played for their national senior team. Their strong point is their teamwork."
However, the German-Brazilian tactician said Thailand also have several fine players to face Shin Tae-Yong's men.
"Our players have quality and have been doing a good job. They are the future of the national team," he said.
"I think Indonesia did very well in the group stage. But I am confident that Thailand are good enough to qualify for the final."
Polking said Thailand would try to finish off the Indonesians in 90 minutes.
"If the game needs extra time or a penalty shoot-out, it could go either way," he said.
The men's football tournament at the SEA Games is for U23 players.
Thailand will play Indonesia at Thien Trurong Stadium in Nam Dinh thanks to the Young War Elephants' top spot in Group B.
Thailand played all their group games at the same venue.
"We don't have to travel. We have already played four matches at the stadium," Polking said.
"It is good for us to stay at the same place in the semi-finals."
Polking is normally the coach of the Thai senior side but has been appointed to take charge of the U23 team at this SEA Games.
He guided the Thai national team to win the AFF Suzuki Cup in January after beating Indonesia over two legs.
Thailand are the most successful nation in the men's football at the SEA Games with 16 titles.
However, they were eliminated in the first round at the previous Games in 2019.
