Congo won their first game at an Africa Cup of Nations finals since 1974, beating Gabon to move top of Group A.
The Gabonese enjoyed the better of the first half but fell behind after 48 minutes when Prince Oniangue stabbed the Red Devils in front from a corner.
Charlton Athletic’s Frederic Bulot, who had a fine early volley saved, wasted Gabon’s best chance, missing an open goal midway through the second half.
Gabon 0-1 Congo | Africa Cup of Nations 2015
A draw against Burkina Faso on Sunday would take Congo to the quarter-finals.
Whoever wins between Gabon and Equatorial Guinea in Bata on Sunday will also qualify for the last eight.
Gabon dominated the early exchanges, playing with confidence after their 2-0 win over Burkina Faso on Saturday.