Nigeria were made to work hard to beat Angola, who were aiming to make it to the semifinals for the first time in their history.
On the stroke of halftime, Moses Simon set up Lookman, who calmly slotted past custodian Guilherme da Costa to give Nigeria the lead.
The Palancas Negras almost equalized soon after the break when substitute Abrosini Salvador was sent through one-on-one but could only hit the post, leaving the game 1-0.
Nigeria will face the winner of tonight’s quarter-final between Cape Verde and South Africa for a place in the final.
Meanwhile, Congo’s quest for their first AFCON trophy in 50 years continued on Friday after coming from behind to beat Guinea 3-1.
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Chancel Mbemba, Arthur Masuaku, and Yoane Wissa scored the goals for Congo, while Guienea’s only goal was scored from the spot by Mohamed Bayo.
The Leopards will face the winner between host Ivory Coast and Mali in the semifinals.