Senegal reached the semi-finals of the All Africa Games when beating Uganda 2-1 in Maputo on Thursday.
The defeat leaves Uganda bottom of Group B and fighting for survival.
But a heavy defeat for Cameroon when they meet Senegal on Sunday could still put the Ugandans through.
Senegal currently lead three-team Group B with three points, two more than Cameroon - who drew their opening match with Uganda.
The Senegalese opened the scoring on the half-hour when Aliou Coly struck from long-range, before Dame Diop doubled the lead after 56 minutes.
Uganda got back into the game after Juma Ibrahim converted a penalty ten minutes from time, but Senegal held on for the win.
In the women's event, Ghana made it through to the last four after beating Zimbabwe 2-1 in Group B.
They now top the group with six points, two more than second-placed South Africa following their 2-2 draw with Tanzania, who have one point.
Samantha Skiti opened the scoring three minutes after the break for South Africa, but Tanzania equalised within six minutes through Khamis Mlenzi.
Chantelle Esau then gave Banyana Banyana the lead again only for the Tanzanians to reply within 60 seconds through Khamisi Rashidy.
Tanzania's hopes of reaching the semi-finals now depend on beating Zimbabwe in their final match on Sunday, and hoping that South Africa lose against Ghana.