Qualifiers Brunei made things difficult for the defending champions at the beginning of the game but Port winger Bordin Phala gave the War Elephants a 1-0 lead in the 19th minute before Teerasil Dangda, the tournament all-time top scorer, made it 2-0 before half-time with his 20th goal of the biennial event.
Thailand were dominant in the second half but only managed to increase their lead through an own goal by Yura Indera Putera in the 88th minute, reports the Bangkok Post.
The War Elephants got the fourth goal as the match headed into stoppage time. Sasalak Haiprakhon was fouled by Putera in the area and substitute Peeradol Chamratsamee converted the resulting penalty.
Peeradol got his second goal of the night and the fifth for Thailand in the third minute of added time as the champions wrapped up their opening match in convincing fashion.
“I am very happy with the team’s performance today because we knew very well that the first game is always difficult,” said Thailand coach Mano Polking.
“We won the game and scored five goals and that was very good for the team. We created a lot of chances and our ball possession was good. Now we are looking forward to our next game.”
In Tuesday’s other Group A game, Cambodia defeated the Philippines 3-2 in Phnom Penh. Indonesia are the other team in the pool.
Thailand next face the Philippines at Thammasat Stadium on Monday (Dec 26).