Nigeria finished as Group B runners-up behind Madagascar and have been paired against Clarence Seedorf's men, who settled for the second place in Group F, after a goalless draw against Benin on Tuesday.
Saturday's meeting between the West African countries in Alexandria will be for a place in the quarterfinals of Afcon.
Adepoju, who was a member of the Super Eagles' team which lost to Cameroon at 2000 Afcon final in Lagos, urged Gernot Rohr's men to take Madagascar setback as motivation for the crucial fixture.
"Nigeria should be prepared for a tough game. Cameroon will always be Cameroon even though the team has changed from what he faced back then," Adepoju told Goal .
"Nevertheless, they are always a tough opposition and whenever they are playing against Nigeria, it is always tough and a war.
"I believe our Nigerian team is capable. They should forget about what happened against Madagascar and face the next challenge.
"Losing to Madagascar should be a kind of motivation for the match against Cameroon because Nigerians are counting on them.
"They should up their game and change their attitude. They should give their best because I believe Cameroon will be more motivated in the next round."
Nigeria won the continental title in 1980, 1994 and 2013, and they are in the hunt for their fourth triumph in Egypt.