Defending Asean champions Thailand and last year's runners-up Indonesia were drawn in Group A for the first round battles of this year's competition which has been renamed the Mitsubishi Electric Cup.
The War Elephants overwhelmed the Indonesians 6-2 over two legs in January to win Thailand's sixth title when the competition was played on a centralised basis in Singapore, a year later than scheduled due to the Covid-19 pandemic.
The Philippines, Cambodia and the winners of a play-off between Brunei and Timor-Leste will join Thailand and Indonesia in Group A.
Vietnam, who claimed the top honours in 2008 and 2018, are the top seeds in Group B, which also features 2010 champions Malaysia, four-times winners Singapore, Myanmar and Laos.
The competition will revert to a home-and-away format for the first time since 2018, with group matches beginning on Dec 23.
The top two nations in each of the five-team groups will advance to the semi-finals, which will be played over two legs before the final on Jan 12 and 15.
Thailand coach Mano Polking said the Asean championship will be "a different tournament this year.
"It will be played on home-and-away basis so we will get a lot of Thai fans to cheer us at home games.
"Now that we know the teams in Group A, we will start charting our strategy to defend the title.
"We cannot underestimate any team, they are all good. And it's never easy to defend a title but we will be well prepared for the tournament."
Rabbits' first game
Former Thai League champions BG Pathum United kick off their bid for this year's crown today when they take on Chonburi in an away game.
It will be the Rabbits' first league game of the season as they were away participating in the knockout stages of the AFC Champions League in Japan, where they eventually lost in the quarter-finals to Urawa Red Diamonds 4-0 of the host country on Aug 22.
Pathum coach Makoto Teguramori is expecting a tough game at Chonburi.
"This will be our first match in the domestic league this season and it won't be an easy opener for us," he said.
"Chonburi are a good team. Although they lost their last game to Buriram United, they have shown that they can play a close game with the big teams.
"We will field our best squad as our target is to pick up three points from this game." Bangkok Post/Reuters
