Kick-off is at 19h00 South African time at Stade Caroline Faye in M’bour, Senegal.
South Africa need a win or a draw to advance to the semi-finals of the competition along with Group A winners Senegal.
Da Gama has made two team changes since a 3-2 win over Zambia on Tuesday, bringing in Phumlani Ntshangase and Siphelele Ntshangase for the attack-minded Phakamani Mahlambi and Dumisani Zuma.
Jody February retains his place in goals, and the rearguard of Tebogo Moerane at left-back, Abbubaker Mobara at right-back, and central defenders Rivaldo Coetzee and Kwanda Mngonyama, remains the same.
Mobara has been declared fit to play after he shrugged off the groin injury he sustained against the Zambians. He trained on Thursday afternoon without any signs of discomfort and managed to complete the session.
There is one change in midfield and one upfront.
P. Ntshangase comes in to work alongside captain Keagan Dolly, Deolin Mekoa and Menzi Masuku in the middle of the park.
The new attack will be formed by Gift Motupa and S. Ntshangase.
A defeat will see Tunisia progress in the tournament, which serves as a final qualifier for next year's Olympic Games in Brazil.
The top three finishers at the event will secure a spot at Rio 2016.
SA U-23 XI:
Jody February (GK), Kwanda Mngonyama, Rivaldo Coetzee, Tebogo Moerane, Abbubaker Mobara, Keagan Dolly (c), Gift Motupa, Phumlani Ntshangase, Siphelele Ntshangase, Menzi Masuku, Deolin Mekoa.
Subs:
Ricardo Goss (GK), Kyle Peters (GK), Tshepo Rikhotso, Zitha Macheke, Denwin Farmer, Riyaad Norodien, Sibusiso Sibeko, Paseka Mako, Phakamani Mahlambi, Dumisani Zuma.
Tunisia XI: Ben Hsa, Kechrida, Kchok, Mechan, Yassine, Jelassi, Khelil, Abd, Jouini, Ghandri, Mansour.