Youssef Msakni struck as Covid-hit Tunisia stunned 10-man Nigeria 1-0 to advance to the Africa Cup of Nations quarter-finals.
The Tunisia captain powered home a low shot from outside the penalty area two minutes into the second half to bundle Nigeria out of the tournament.
Nigeria had been the only side to win all three of their games in the group phase and were overwhelming favourites as Tunisia battled without seven players, who were isolating because of Covid-19.
But Tunisia, who also had to do without coach Mondher Kebaier because of Covid-19, advanced to meet Burkina Faso in next Saturday’s quarter-final in Garoua.
There were few chances in the game with Tunisia producing a stout defensive performance and looking for counter-attacking opportunities.
Nigeria were unable to get any flow to their play, despite having beaten Egypt, Sudan and Guinea Bissau in their earlier games.
They were reduced to 10 men when Alex Iwobi was sent off for a dangerous tackle in the 66th minute, seven minutes after coming on.
The referee originally handed him a caution but was encouraged to review the sanction on the pitchside VAR screen, before changing his mind and sending Iwobi off.
The 31-year-old Msakni, competing in his seventh Cup of Nations finals but starting his first match of the tournament, was given time to line up his shot and it swerved to catch out the Nigeria goalkeeper Maduka Okoye, who only managed to get a hand to it.
„We got punished for one mistake,“ said Nigeria coach Augustine Eguavoen.
„Alex should not have been given a red card but the referee saw it differently. But congratulations to Tunisia.“
It was a remarkable turnaround for the North Africans, who had lost two of their three opening-round games, including an embarrassing 1-0 defeat to Gambia three days ago.
They managed to get some players back out of isolation ahead of Sunday’s match but assistant coach Jalel Kadri had to take over for the game.
Nigeria threw players forward near the end and substitute Umar Sadiq might well have forced a stoppage-time equaliser but his effort went agonisingly wide of the goal.
AFCON 2021 round-of-16 fixtures and results
Burkina Faso 1-1 Gabon, (Burkina win 7-6 on penalties)
Nigeria 0-1 Tunisia
Monday January 24
Game 3: Guinea vs Gambia, 4pm (Kouekong Stadium, Bafoussam) – Live on Sky Sports Football
Game 4: Cameroon vs Comoros, 7pm (Olembe Stadium, Yaounde) – Live on Sky Sports Premier League
Tuesday January 25
Game 5: Senegal vs Cape Verde, 4pm (Kouekong Stadium, Bafoussam) – Live on Sky Sports Football
Game 6: Morocco vs Malawi, 7pm (Stade Ahmadou Ahidjo, Yaounde) – Live on Sky Sports Premier League
Wednesday January 26
Game 7: Ivory Coast vs Egypt, 4pm (Japoma Stadium, Douala) – Live on Sky Sports Football
Game 8: Mali vs Equatorial Guinea, 7pm (Limbe Stadium, Limbe) – Live on Sky Sports Premier League
The Africa Cup of Nations tournament will be broadcast live on Sky Sports in January and February.
The tournament, originally scheduled to be played in June and July 2021, will be played in Cameroon between January 9 and February 6, 2022, with Sky Sports showing all 52 games live.
Twenty-four teams will take part, kicking off on January 9 as hosts Cameroon host Burkina Faso in Yaounde, before culminating in the final on February 6 in the capital.