Victor Osimhen starred as Nigeria became the second qualifiers for the Africa Cup of Nations knockout stage after Egypt by surviving a late Tunisia onslaught to win 3-2 in Fes.
The Super Eagles were cruising to victory on Saturday, leading 3-0 through goals from Osimhen, captain Wilfred Ndidi and Ademola Lookman.
But Tunisia refused to surrender in the top-of-the-table Group C clash, and Montassar Talbi and Ali Abdi scored to set up a tense finish.
Tunisia had two chances to level during seven minutes of added time, but a header from captain Ferjani Sassi and a shot by substitute Ismael Gharbi were just off target.
Nigeria have six points, Tunisia three, and Tanzania and Uganda one each, with the final round of group matches set for Tuesday.
The showdown was the seventh time the Super Eagles and the Carthage Eagles had faced each other at an AFCON.
Nigeria won three times, and Tunisia once. Another two meetings went to penalty shootouts, with each nation winning one. After performing well below par when edging Tanzania in the opening round, Nigeria were a transformed team against Tunisia, dominating the first 30 minutes in the northern city. Osimhen was outstanding, particularly in aerial duels, while Tunisia were forced to constantly defend against the three-time champions.
The Galatasaray striker, wearing his trademark mask, headed just over after nine minutes, and came close again soon after as he rose to meet a corner kick.
Osimhen had the ball in the net after 17 minutes, but was rightly ruled offside. Big-screen replays showed the 2023 African player of the year timing his run too early.
Tunisia midfielder Hannibal Mejbri was lucky to escape a yellow card for dissent after reacting angrily when a Nigerian took a foul throw, flinging the ball into the ground.
Osimhen was wide with another headed goal attempt, then left the pitch temporarily so that the medical staff could apply a spray to his leg.
Tunisia finally broke out of a defensive shell on 32 minutes and forced a corner. The set-piece ended with the ball coming back to Abdi, whose shot flew well over.
Several Tunisian raids reaped no reward, and on 44 minutes, the goalless deadlock was broken, with Osimhen, predictably, the scorer.
The goal involved two former African players of the year, with 2024 winner Lookman crossing the ball and Osimhen rising between Abdi and Talbi to head powerfully into the net.
Just five minutes into the second half, Nigeria stretched their lead to two goals, as they once again exposed the aerial weaknesses of the Tunisian defence.
Atalanta striker Lookman was the architect again, floating a corner into the heart of the goalmouth, where Ndidi soared to beat goalkeeper Aymen Dahmen and score his first international goal. After creating the first two goals, Lookman scored the third on 67 minutes, after being set up by Osimhen. He had time to control the ball in the box before slamming it into the net off the post.
Tunisia pulled one goal back with 16 minutes remaining. The North Africans finally got the better of an aerial duel, and Talbi nodded a Mejbri free-kick into the net.
The goal had a dramatic effect as Tunisia took control and scored again with three minutes left, when Abdi converted a penalty awarded after a VAR review showed Bright Samuel handled.