Thailand aim to retain the Asean title after reaching the semi-finals of the AFF Mitsubishi Electric Cup.
The War Elephants topped Group A ahead of Indonesia on goal difference after a 3-1 win over Cambodia at Thammasat Stadium on Monday night.
Teerasil Dangda scored twice for the home team and Sumanya Purisay added the other.
Teerasil's penalty put the hosts in front just before the interval and Sumanya made it 2-0 shortly after the restart.
Sieng Chanthea netted for Cambodia midway through the second half but Teerasil was on target again in the dying moments.
"Our target is clear -- to defend the title," said Thailand coach Mano Polking.
"However, to win the title again we must play better than we did today. Cambodia played like many underdogs at the  World Cup. They played with defensive intent and waited for counter-attacks.
"We need improvement for the next game. We wanted to be Group A winners because we will play the semi-final second leg in front of our fans."
Teerasil, the event's all-time top scorer with 24 goals, said he was happy to score two more goals.
He added that Thailand must be well-prepared for the semi-finals.
"In a tournament, fitness is very important. The players must recover before the next game," he said.
Group A winner and defending champions Thailand will next play Group B runners-up Malaysia in the semi-final first leg on Friday and the return match in Bangkok on Jan 9.
Malaysia handed Singapore a 4-1 thrashing in Kuala Lumpur on Tuesday, while Vietnam will take on Indonesia after their 3-0 victory over Myanmar in Hanoi.
The two-legged final is scheduled for Jan 13 and Jan 16.
Thailand are the most successful team in the Southeast Asian championship with six titles.