Senegal had not enjoyed a better part of possession facing Tunisia side applying pressure in an attempt to get an early goal of the second match on day two of AFCON 2017 once the referee blew for kick off.
They emerged top with a 2-0 victory over Tunisia who will face Algeria.
Algeria and Zimbabwe had tied at a 2-2 draw leading group B that had been termed the toughest with potential top contenders.
Into the tenth minute Kouyate in was brought down and Sagio Mane successfully converted.
Kara Mbadji's header from a corner kick gave Senegal the second goal.
Senegal proved up to the task defending the lead to full time whistle and now have a better chance to proceed to the quarter finals as they face Zimbabwe.
In his tenth debut for his national team, 24-year-old Senegal goalkeeper Abdoulaye Dialo with outstanding man of the match performance gave records the first victory for this year's tourney.
Tunisia has had an impressive ten match unbeaten record to this day creating cracker chances but only match statistics were in their favour.