The Thai men's football team face Myanmar in the semi-finals of the SEA Games in Cambodia on Saturday.
The Thai U22 side drew 1-1 with Vietnam on Thursday to top Group B.
Group B champions Thailand take on Group A runners-up Myanmar and Group B runners-up Vietnam meet Group A winners Indonesia in the semi-finals on Saturday.
Although Thailand coach Issara Sritaro rested a large number of his key players during the match against Vietnam, he said he was worried about the players' fitness.
"We will have a day's rest while Myanmar get two full days to recover. If all the players are fit for the match, I am confident we will reach the final," said Issara.
"Myanmar have good speed and they keep on fighting. We have some homework to do and must be brave to play our own game.
"The Olympic Stadium is a good venue which should encourage our players.
"We will try our best to finish the match in 90 minutes but if it has to be decided by a shoot-out then we have players ready for that as well."
Thailand are the most successful nation in the men's football competition at the biennial event with 16 titles.
However, the Thais have failed to claim the title at the previous two tournaments which were won by Vietnam.
Meanwhile, Sritaro said he was not "disappointed" by the 1-1 draw with Vietnam.
Despite the tie, the War Elephants topped the group standings with a better goal difference after both Thailand and Vietnam finished with 10 points each from four matches.
The Thais started well when Achitpol Kirirom put them ahead in the second minute but Vietnam equalised through Le Quoc Nhat eight minutes into the second half.
Issara said that it was "good result" for the team.
"We met our target of finishing first in the group so I am not disappointed by the draw," said the coach.