The Thai women's football team begin their campaign to reclaim the SEA Games title against Singapore at Quang Ninh in Vietnam on Tuesday.
In other Group B game, Myanmar take on Laos.
In Group A are hosts Vietnam, the Philippines and Cambodia.
The top two teams in each group advance to the semi-finals of the biennial event.
Vietnam (six) and Thailand (five) are the only two nations to have won the women's football title at the SEA Games.
The Vietnamese have been crowned champions in the previous two Games after defeating Thailand in the title match on both occasions.
Thailand coach Miyo Okamoto said this is the Chaba Kaew's first tournament after the AFC Women's Asian Cup earlier this year.
"Our players look excited to be here and play football again," the Japanese coach said.
"It is an important tournament and we are here as representatives of Thailand. We have several new players and I hope they get experience."
Thailand are expected to meet Vietnam in the final.
However, Okamoto said the ultimate goal is to help Thailand seal a berth at the 2023 Women's World Cup.
"Our main target is to qualify for the World Cup. This is a venue for us to prepare for the qualifying tournament," Okamoto said.
The Chaba Kaew have played in the 2015 and 2019 World Cup finals.
They failed to earn an automatic World Cup spot at the AFC Women's Asian Cup and will now have to play in a play-off tournament.