A goal from Seydouba Soumah was enough to ensure Guinea qualified for the finals of the Africa Cup of Nations with a 1-0 win over Group A leaders Mali.
The Partizan Belgrade midfielder scored the only goal of the game after 75 minutes.
It means that both teams have safely qualified for the 2021 Africa Cup of Nations Finals - which will actually be played in 2022, in Cameroon.
Namibia and Chad did not play in the opposite fixture in the group, as Chad have been disqualified from the competition as a result of government interference in the country's Football Federation.
Although this meant Namibia were automatically awarded a 3-0 victory over Chad, Guinea's victory means that they cannot finish higher than third.
Namibia will now play Guinea on Sunday, when Mali will likewise be awarded a 3-0 win over Chad by default.