Thailand beat Singapore 3-0 on Sunday to advance to next week's semifinals of the Asean Football Federation Championship along with Sven-Goran Eriksson's Philippines.
Singapore needed to win against the defending champions to force their way into the top two in Group B of the regional championship yet their three-goal defeat means Thailand finish top of the standings while the Philippines take second after a 0-0 draw with Indonesia.
Thailand will face Malaysia in their semifinal, which will be played over two legs on Dec. 1 and 5, while Vietnam face off against the Philippines on Dec. 2 and 6.
Thailand fielded a weakened side but still took the lead 12 minutes into the game against the four-times winners when Irfan Fandi put the ball in his own net.
The back-to-back defending champions added a second 11 minutes later when Supachai Jaided beat Singapore goalkeeper Hassan Sunny low at his near post before Adisak Kraisorn claimed his side's third and his eighth goal so far in this year's competition with a minute remaining.
The win was Thailand's third in four games in the 2018 edition and means they top the group with 10 points, two ahead of the Philippines with Singapore finishing on six points to miss out on the last four.
Former England manager Eriksson's team had the better of the chances in their clash with already-eliminated Indonesia, with Stefan Schrock and Manny Ott spurning opportunities to give the Azkals the lead.
In the end, however, the point was enough to take the Philippines into the semifinals for the fourth time in five tournaments as the Azkals seek to progress to the final of the biennial competition for the first time in their history.