Senegal and Algeria are now due to face off to win the 2019 Africa Cup of Nations (AFCON) title in Friday's final in the Egyptian capital Cairo, Anadolu Agency reported.
Tunisia earned a penalty on 73 minutes after Koulibaly's handball in the area, a decision which was upheld after a VAR check, but Sassi failed to capitalise through a strong save from Gomis.
Nigeria were the better side in the second period for few moments, and it always looked the Algerians were the side to grab the victor.
Nothing separated the sides at the end of a pulsating 90 minutes and they were pushed into extra time where Senegal emerged as 1-0 winners courtesy an own goal from defender Dylan Bronn.
Cisse, Senegal's captain at the time, missed a vital penalty for Senegal during the shoot-outs. Senegal livened up their structure two minutes later, as Ismaila Sarr replaced Krepin Diatta on the wide side. Tunisia had the first after 72 minutes which Ferjani Sassi missed while Senegal had their own in the 80th minute, missed by Henri Saivet.
In extra time, he went to punch away a free kick swung over from the right wing, but only forced it onto Bronn's head and it rebounded into the net.
The Tunisians are yet to suffer defeat in the tournament so far, while the victory over Madagascar was the first from open play, having defeated Ghana on penalties.
After a tense delay, he ran back onto the field waving his arms to signal no penalty.
"They have a team that has played together since the World Cup and I strongly believe they will take the title".
Senegal will wait for the victor between Nigeria and Algeria in the other leg of the semifinals to know their opponents in the finals.
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