Napoli star Victor Osimhen scored a hat-trick in Uyo as Nigeria thumped Sao Tome e Principe 6-0 in Group A, having won the first-round match 10-0 last year.
He headed in from a corner on 14 minutes, converted a 70th-minute penalty after being fouled by goalkeeper Ronaldo Silva, and netted with a close-range shot 10 minutes later.
Ademola Lookman scored the second goal with a low shot after a run across the edge of the area to give the Super Eagles a two-goal halftime advantage in heavy rain.
Taiwo Awoniyi struck with a close-range shot six minutes after the break and, after Osimhen netted twice, Samuel Chukwueze completed the rout.
It was the fifth victory in six mini-league matches for three-time champions Nigeria, whose sole blemish was a stunning 1-0 home loss to Guinea-Bissau.
In Lome, Togo came from two goals behind to defeat already-qualified Cape Verde 3-2 with Abdou Ouattara snatching the 87th-minute winner.
Kevin Pina and Gilson Tavares scored early goals for the visitors in the final Group B match before Kevin Denkey netted twice to bring the teams level.
Cape Verde finished runners-up behind Burkina Faso and both will be among the 24 title contenders in the African showpiece.