Singapore have dropped 12 spots to 161st in the latest batch of world rankings.
The country is now behind neighbours Malaysia and Indonesia and just in front of Guam.
A 2-1 loss to Hong Kong (163) and a 2-2 draw with Macau (184) earlier this month has done Singapore no favours, as the country is now only four spots away from it's worst ever ranking of 165.
Meanwhile, Myanmar, who are coached by former Singapore coach Raddy Avramovic have risen 6 spots to 137th in the world and will now face Singapore in the group stages of the AFF Suzuki Cup after a fine qualifying campaign.
Singapore's other group stage opponents are Malaysia at 156th and Thailand at 165th in the world.
Other Southeast Asian rivals in action this November include the Philippines (129), Vietnam (136), Laos (154) and Indonesia (157).