Three-time men's football defending champions Thailand's quest for a place in the semi-finals of the 2019 SEA Games hinges on many factors, some of which being beyond their control.

The War Elephants take the field on Tuesday for their fourth Group B game with Loas, which they are the favourites to win with ease. The match at Manila's Rizal Memorial Stadium will be televised live by Channel 7, starting 3pm.

However, it will be the upshot of their last group battle with arch-rivals Vietnam on Thursday which will prove decisive.

Thailand and Indonesia both have six points each after three matches, but the War Elephants, who beat Singapore 3-0 on Sunday, are ranked second as they have a far superior goal difference. Vietnam lead the group with perfect nine points with the top two teams advancing to the next round.

What makes things tough for the Thais is the fact that the Indonesians are scheduled to play their remaining two against minnows Brunei (Tuesday) and Laos (Thursday).

This leaves Thailand with no margin for error, making it imperative for them to win their both remaining group games and hope that Indonesia either slip up or fail to better their goal difference.

Thailand coach Akira Nishino confirmed after Monday's training session that it may all boil down to the goal difference in the end.

"The number of goals are very important but we have to check the fitness of our players first," said Nishino.

"We have to focus on winning the game against Laos first and then think about the number of goals."

Nishino, who was at the venue to witness Vietnam pull off a 2-1 victory over Indonesia with a last-gasp goal on Sunday, added: "The Vietnamese have variety in their attack and their teamwork is also very good. Their style is very similar to that of their senior national team. In fact, it would come down to how well-prepared we are for the match against Vietnam."