Failure to win will threaten Cameroon's achievement of reaching at least the quarter-finals at the last seven tournaments, stretching back to Burkina Faso in 1998.
A draw might prove enough for World Cup-bound Cameroon to advance but such are the permutations on the final day of Group D action that any slip could allow for surprise early elimination.
Group leaders Gabon meet Zambia in Benguela and could have their hopes of a quarter-final place snatched away.
Gabon have exceeded expectations in beating Cameroon and drawing with Tunisia in their opening two matches but if they lose to Zambia they are likely to be eliminated.
Gabon have four points to Zambia's one but a Zambian win would put them ahead of Gabon in the group rankings by virtue of their head-to-head result.
Cameroon have three points and opponents Tunisia, who have drawn their first two matches, have two but still harbour hopes of advancing.
Tunisia, who won the Nations Cup on home soil in 2004, must beat Cameroon if they are to stand any chance of a quarter-final berth and a measure of consolation for the disappointment of missing out on World Cup qualification.
On Wednesday, Egypt maintained their 100 percent record with a 2-0 win over Benin in Benguela to top Group C while Nigeria beat Mozambique 3-0 in Lubango to finish second.
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