Earlier in the day, the East Africans beat South Africa 2-1 in Addis Ababa to seemingly reach the African play-offs. However, they now face accusations they fielded an ineligible player in the 2-1 win over Botswana on 8 June.
Fifa rules state any team found guilty of that offence "will be sanctioned by forfeiting the match". Football's world governing body is also investigating Togo and Equatorial Guinea for the same reason.
A guilty verdict against all the sides would have serious ramifications in three of the qualifying groups for next year's World Cup in Brazil.
Â The case against the Ethiopians is pressing, as a guilty verdict would hand a lifeline back to 2010 World Cup hosts South Africa.
Currently five points off the top of Group A, South Africa would only be two points behind if the Ethiopians have to forfeit their victory against Botswana - and receive a technical defeat instead.
The announcement of Fifa's probes will not only encourage South African football fans, but also those of Cameroon and Cape Verde. Cameroon were beaten 2-0 by Togo on 9 June but the six-time World Cup qualifiers now stand to gain the three points should the Togolese be found guilty. Such a scenario would move Cameroon, who currently trail Group I leaders Libya by two points, a point clear in the table.
The West Africans host Libya in what is both sides' final encounter in September. Equatorial Guinea allegedly fielded an ineligible player in their 4-3 defeat of island nation Cape Verde in March.
Fifa says they recently ruled on that matter and that the 2012 Africa Cup of Nations co-hosts have appealed the decision. Should island nation Cape Verde receive the points from a match they originally lost, the passage of Tunisia to the African play-offs would also be in question.
The Carthage Eagles drew 1-1 in Equatorial Guinea on Sunday to seemingly book their place, but a technical victory for Cape Verde would lift the islanders up to nine points - just two behind the North Africans.
Tunisia host Cape Verde on the final day of the current qualifying stage.