Keita struck twice within six first-half minutes to help Senegal overcome South Africa 3-1 in the opening match of Group A and the 15-day competition at Stade Leopold Sedar Senghor in Dakar. The second game of a double-header at the 60,000-seat national stadium was closer with Jouini completing his brace six minutes from time to earn Tunisia a 2-1 win over Zambia.
South Africa were the more impressive side before falling behind when Keita converted a 16th-minute penalty after flying winger Ismaila Sarr was pushed off the ball. When the visitors conceded possession cheaply in midfield soon after, Samba Ndiaye set up Keita to score again with a close-range flick past goalkeeper Ricardo Goss.
Substitute Sidy Sarr assured Senegal of victory three minutes from time when he collected a throw with his back to goal, half turned and fired the ball across Goss into the far corner.
Giant striker Jouini headed Tunisia in front on four minutes off a corner only for Ronald Kampamba to level after 16 minutes with an audacious long-range shot over poorly-positioned Sabri Ben Hassen. Tunisia created the better second-half chances and deservedly regained the lead when Jouini nodded a Saad Bguir cross past goalkeeper and captain Toaster Nsabata at the far post.
Group B kicks off Sunday with Algeria playing Egypt at Stade Caroline Faye in M'Bour, 70 kilometres (44 miles) south of Dakar, followed by Mali against Nigeria at the same venue.
The top two countries in each mini-league advance to the semi-finals and those finishing first, second and third qualify for the Rio Olympics.