Before the Asian Cup kicked off in Qatar, Vietnam were 94th in the FIFA rankings with 1,235.58 points. They will be updated on Feb. 15.
Vietnam lost 6.47 ranking points after losing 2-4 to Japan and 23.26 points for losing 0-1 to Indonesia.
They now have 1,205.85 points and dropped to 99th.
They will lose 11.33 points if they lose their last group match to Iraq, and are likely to exit the top 100.
A draw will fetch 6.17 points and a win, 23.67.
As of Tuesday Vietnam have been in the top 100 for 1,882 days since Nov 29, 2018. They have ranked first in Southeast Asia for 2,225 days.
Thailand are closing in on Vietnam and are on 1,198.95 points after gaining 22.97 points from their victory over Kyrgyzstan and draw against Oman.
They have climbed 11 places to 102nd.
A draw against Saudi Arabia will fetch them 7.75 points and an unlikely win, 25.25, enough to launch them into the top 100.
With a high chance of advancing to the round of 16, they will have at least one more match to improve their position.
Meanwhile, thanks to their important victory over Vietnam, Indonesia climbed four places to 142nd.
Malaysia, after losing two matches, fell five places to 135th.
The FIFA world rankings, usually updated every one or two months, are based on the coefficient of the matches.
Friendly matches only have a coefficient of 10, while it is 35 for Asian Cup matches before the quarterfinals and 40 after that.
FIFA’s formula also considers the difference in strength between the teams, with the lower ranked team getting more points for a win and losing fewer for a loss.
The rankings are used for seeding teams in FIFA tournaments such as the World Cup and Asian Cup.