Thailand manager Nualphan Lamsam vowed to bring back the fans' faith following Tuesday's draw for the 2020 AFF Suzuki Cup.
Five-time champions Thailand were drawn into Group A with Myanmar, the Philippines, Singapore and Brunei or Timor Leste.
Holders Vietnam are in Group B with Malaysia, Indonesia, Cambodia and Laos.
The tournament, postponed from last year due to the Covid-19 pandemic, is scheduled to begin on Dec 5 and end on Jan 1.
The event will be held in a centralised venue after the Asean Football Federation (AFF) scrapped plans to play on a home-and-away basis due to concerns about travel and safety amid the coronavirus outbreak.
The host country for the biennial championship is yet to be determined.
"We must try to bring back our fans' faith," said Nualphan. "It is a challenging task. Although we are five-time champions, we can't underestimate any team. To become six-time champions, we must be at our best. Teams like Myanmar, the Philippines and Singapore all want to win the title."
The Football Association of Thailand (FAT) appointed Nualphan as manager of the men's senior and U23 teams last month.
The move came when the FAT sacked coach Akira Nishino after the War Elephants were eliminated in the qualifying round for the 2022 World Cup.
The national senior side are still without a coach to succeed Nishino.
Nualphan earlier said she was considering hiring a Thai or a foreign coach. She also called on parties concerned to bring the tournament to Thailand.
The Thais will begin their campaign against the winners of a play-off between Brunei and Timor Leste on Dec 5.
