The Super Eagles dropped from 47 to 48 in the June world rankings released by FIFA on Thursday.
Nigeria could not maintain their spot in May due to losses from their pre-World Cup friendlies and slid down a spot in June. The Eagles could only win one of their last five friendly matches since March.
In the rankings, the Eagles have 618 points against the 635 points they had in the May rankings. They are currently seventh in Africa.
Tunisia, who were ranked 14th in May, dropped to 21st. They have 910 points. Senegal (27) with 838 points climbed a spot from their May rankings and are now second in Africa.
DR Congo (38), who played a 1-1 draw with the Eagles in Port Harcourt in May, are third in Africa after they maintained their place on the rankings. CHAN 2018 hosts and champions Morocco are 41st in the world and fourth on the continent. The Atlas Lions moved a spot with 686 points.
Egypt climbed a spot to 45th in the world and are now fifth in Africa while Ghana moved up three places to sit above Nigeria in sixth position. They are ranked 47th in the world.
Cameroon (49), Burkina Faso (52) and Mali (64) complete the continental top 10.
Nigeria’s Group D Russia 2018 European opponents Croatia dropped two spots while Iceland and Argentina retained their places in the rankings.