The Thai team ranked 113th in the world, defeated Kyrgyzstan 2-0 last Tuesday in the opening match.
Currently, the team is focusing on full recovery of its injured players so it can play at full strength against Oman, who are ranked higher at 74th in the world.
At Thursday's training session, coach Masatada Ishii of Japan emphasised strength training and precision in ball passing.
Oman had lost 2-1 to Saudi Arabia in their opening match and would need to avoid losing to Thailand to keep alive their chances of advancing to the next round.
Former Thai national player Chalermvud Sangapol said: "The pressure is on Oman because of their previous loss. This gives Thailand the chance to play a more defensive game, putting pressure on the rivals."
Sasom Pobprasert, another former football player, said: "At this point, the Thai national team still has a chance to reach the quarterfinals if they are physically prepared.
Although the upcoming game will be challenging, there is still an opportunity to be among the 16 teams that advance to the next round."
Another former football player Teeratep Winothai believes that the Japanese coach could contribute to the team's performance.
"Currently, there is a 70% chance of advancing to the next round, but the team must play carefully in the game against Oman.
Players from Arab countries tend to have effective playing styles that can disrupt opponents, so the team needs to be well-prepared for the match."
The Thai national team will face Oman at the Abdullah bin Khalifa Stadium at 9.30 pm Thailand time on Sunday.
The match will be broadcast live on PPTV HD channel 36 and T-Sports 7.