Due to injuries to Amine Gouiri and Hamed Junior Traoré, Roberto de Zerbi has heavily relied on Pierre-Emerick Aubameyang, who picked up a left thigh injury during Olympique de Marseille's 1-0 win over Monaco on Sunday night.
The Gabonese Federation has confirmed their star player will miss the opening group match against Cameroon on December 24.
"After discussions with the national team's medical staff, Olympique de Marseille's medical team decided to handle his treatment in Marseille," the official statement read.
"The player will be unavailable for the December 24 match against Cameroon. Depending on his clinical progress and imaging results, he could be available for the December 28 match against Mozambique."
For now, Aubameyang will remain in France and will join the Panthers once he is fit to play.