Nigeria's 100 per cent record in the group stage of the Africa Cup of Nations meant nothing as they crashed out 1-0 to Tunisia in the round of 16.

Youssef Msakni's low, swerving shot just after halftime was the game's only goal, leaving Nigerian players slumped on the field in disappointment at the end.

Nigeria's task against Tunisia was made harder when Everton's Alex Iwobi was shown a straight red card for raking his studs down the ankle of Msakni in the 66th minute.

Iwobi was sent off seven minutes after coming on as a substitute.

Earlier on Sunday, Burkina Faso beat Gabon 7-6 in a penalty shootout to become the first team to book a place in the quarter-finals.

Nigeria had emerged as a top contender for the title after they were the only team to win all three of their group games.

Tunisia lost twice in the group stage and only went through as one of the best third-place teams, but closed Nigeria down in a cagey game in Garoua

Tunisia got the job done without coach Mondher Kebaier, who was isolating in his hotel room after a positive test for coronavirus.

Substitute Ismahila Ouedraogo buried the decisive spot kick for Burkina Faso, as they finally prevailed over battling Gabon in Limbe.

Burkina Faso led 1-0 when Gabon had a man sent off in the 67th.

But 10-man Gabon equalised in injury time through an own-goal by Burkina Faso midfielder Adama Guira to send the game to extra time.

It stayed 1-1 through the extra 30 minutes.

Burkina Faso twice had opportunities to win the shootout after Gabon players missed before Ouedraogo's decisive effort from 12 yards -- the 18th kick of the shootout.

Burkina Faso took the lead in regulation time through a first-half goal by captain Bertrand Traore before Gabon had defender Sidney Obissa sent off with just over 20 minutes to go for a second yellow card.

Obissa had blatantly pulled a Burkina Faso attacker back by the shirt off the ball as the Burkinabes were surging forward.

It capped a miserable day for Obissa, who picked up his first yellow card when he gave away an early penalty for a push on Issa Kabore.

Traore missed that penalty but made up for it 10 minutes later when he ran onto a through ball and slotted his shot into the net.