Former Continent's Best Player of the Year Victor Osimhen was instrumental in Nigeria build a commanding lead, before the Super Eagles were compelled to defend resolutely for a narrow victory.
The three-time champions weathered a dramatic late rally from Tunisia to advance to the knockout stage of the Afcon tournament being held in Morocco.
The Super Eagles appeared to be in complete control in their pool clash in the Moroccan city, holding a 3-0 cushion with just 17 minutes remaining thanks to strikes from their attacking trio.
Yet, Montassar Talbi pulled one back with a powerful header from a Manchester United midfielder free-kick, sparking hopes of a turnaround.
The tension intensified when the North Africans were awarded a late penalty after a VAR review spotted a handball by Bright Osayi-Samuel. Ali Abdi converted in the 87th minute to create a nail-biting finale.
Tunisia were inches away from a stunning equalizer in stoppage time, with captain Ferjani Sassi heading a opportunity just past the post before Ismael Gharbi guided a half-volley past the upright.
The victory means that Nigeria, champions of the competition on three previous occasions, advance to six points and are assured top spot in Group C with a match still to play.
In the next round, they will meet a third-placed team from either the other preliminary groups.
In the other match, the 2004 champions remain on 3 group points, with Uganda and Tanzania locked on one point each after registering a 1-1 draw earlier on Saturday.
The final pool fixtures will see Nigeria remain in Fes to take on Uganda on the next matchday, while the Eagles of Carthage return to the capital to confront the Taifa Stars.
Ali Abdi smashed home from 12 yards to offer his team hope of snatching a point.
Nigeria, runners-up in the 2023 tournament, are the second team after Egypt to qualify for the knockout stage, but their manager and fans will certainly be breathing a sigh of relief.
What looked like set to be a straightforward last period transformed into a tense conclusion.
Victor Osimhen had a effort disallowed for an infringement before opening the scoring right before the interval, precisely placing a header into the far post from an Ademola Lookman delivery.
The lead was doubled soon in the second period when the Leicester City midfielder climbed above everyone to thump in a header from a set-piece corner.
Osimhen then turned provider Lookman for the seemingly decisive goal, only for Montassar Talbi to steer a header past the Nigerian shot-stopper to initiate the fightback.
The key incident came when a high ball hit the arm of Bright Osayi-Samuel, with the official pointing to the spot after reviewing the VAR monitor.
Although Ali Abdi's successful penalty, Tunisia ultimately came up just short of completing a remarkable comeback.
Their fate remains in their own hands; a draw against Tunisia will be sufficient to secure progression, and manager Sami Trabelsi will be keen to prevent a recurrence of the 2013 group-stage exit that led to his departure.
News
News