Nigeria’s Super Eagles will not get the chance to win their fourth title, just yet, after a 47th minute Youssef Msakni strike sent them out of the Africa Cup of Nations.
A cagey first half had it highlights the first of which arrived when Wilfred Ndidi flashed an overhead kick wide as early as the second minute as Nigeria looked to open the scoring.
The first real chance of the evening fell to the Tunisians, but Wilfred Ndidi came to the rescue with a goal-line clearance.
Nigeria responded almost instantly through Joe Aribo, but the Rangers man, after receiving a decent ball from Moses Simon, saw his shot blocked at the last second.
The Carthage Eagles were rattled and could have conceded just past the quarter of the hour, but Taiwo Awoniyi could not get his head to make contact with a side-footed Samuel Chukwueze cross.
The Villarreal winger and Aina combined well on the right flank before the Chelsea academy product sent a low cross into the box which arrived behind Awoniyi.
The rest of the half fizzled out without much Falmouth action as both teams were content keeping the ball away from their area as much as possible.
Moments into the second half, Tunisia broke the deadlock after a fierce Youssef Msakni drive left Okoye with egg on his face.
It was the first time the Augustine Eguavoen-led side would concede the first goal at the Afcon in Cameroon.
The Super Eagles reacted well, raising the tempo, but the ball did not fall kindly to any of Awoniyi or Iheanacho as they pressed for an equaliser.
The evening turned for the worst for Nigeria when the Eagles were reduced to ten men. Alex Iwobi, minutes after coming off the bench, was shown a straight red card for a rash stamp.
Still, Simon should have equalised for Nigeria after a Peter Olayinka cross found him in the box. But goalkeeper Ben Said kept out the Nantes man’s shot.
Okoye saved a fierce Tunisian drive as the North Africans exploited the spaces left behind by the attacking Nigerians.
The Super Eagles were relentless, though, and Simon flashed a free-kick just wide after good work from Umar Sadiq.
Ndidi sent another shot wide when well-placed and Sadiq missed another sitter late on as the crucial equaliser eluded the Super Eagles.
Nigeria’s 100% record in Cameroon ends on a sad note. The Super Eagles leave Cameroon with Tunisia processing to face Burkina Faso in the quarterfinals.