The fresh injury news comes one day after Club Africain striker Saber Khalifa was also ruled out of the Nations Cup. Both men were injured in Tunisia's 1-1 draw with Algeria in a Nations Cup warm-up on Sunday .
Ben Youssef, a 22-year-old forward who completed his move to French outfit FC Metz last week, was instrumental in Tunisia's progress to the Equatorial Guinea finals. triumphant campaign in the African qualifiers.
According to Tunisia's doctor, Khalifa and Ben Youssef need around four weeks of treatment.
Tunisia coach Georges Leekens called up CA Bizertin’s top scorer Edem Rejaibi and Esperance striker Ahmed Akaichi to replace the injured duo.
Tunisia were drawn in Group B alongside Zambia, Cape Verde and DR Congo.
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