Based on the ASEAN Football Federation (AFF) meeting in Indonesia on Friday, Thailand and Vietnam are seeded in the top pot of 2018 AFF Cup, which allows them to avoid each other in the group stage.
From next year, newly-formatted AFF Cup will be expanded to include 10 nations from its current eight, with the countries ranked 10th and 11th have to face each other in a playoff for a spot in the main competition.
In the group stage, five teams in the two groups will play two home and two away games, based on the draw conducting by AFF, before the knockout stages.
The top two teams from each group will progress to the semifinals. The semifinals and final will remain two-legged, home and away.