Vietnam were deducted 13.68 points, from 1222.9 to 1209.22, dropping from 98th to 99th. They are only four points away from exiting the top 100.
The Golden Dragons played two home matches in the final round of World Cup qualifiers in November, against Japan and Saudi Arabia. Both games ended with the score 0-1 for the away teams. Vietnam have lost all six games so far in the final World Cup qualifying round, placing bottom in group B.
Vietnam are still the only Southeast Asian team in the top 100.
In Asia, Vietnam are 18th, with the top three spots taken up by Iran, Japan and South Korea.
The world top three teams remain Belgium, Brazil and France.
Vietnam had fallen out of Asia’s top 15 for the first time in two years in FIFA’s world rankings last month, after two World Cup qualification losses against China and Oman.
The Golden Dragons will have the chance to improve their ranking when they play AFF Cup, as defending champions, next month.