The north Africans kicked off their Group C campaign with a 2-1 victory over Morocco and could book a place in the last eight with another win against the unfancied Mena in Libreville.
Striker Khlifa picked up an anterior knee ligament injury during Monday's victory, which a scan has since shown to be inflamed but not torn.
The 25-year-old, who set up Tunisia's opening goal, remains enough of a doubt for Trabelsi to err on the side of caution on Friday - with team doctor Faisal Al Khashnaoui revealing a realistic target would be the final group game against Gabon on Tuesday.
"It is possible that he could be ready for Friday but it will be a bit difficult. He has a much bigger chance of being ready for the one after that," Khashnaoui said in quotes reported by kickoff.com.
"He has a simple anterior knee ligament injury and he'll be back to the team as quickly as possible."
Should the Carthage Eagles play safe with the Evian frontman it could mean a return to action for Auxerre striker Issam Jemaa, who has been out with a hamstring problem.
Meanwhile, Niger technical advisor Rolland Courbis is frustrated that tomorrow's game has an air of make-or-break about it after their opening 2-0 reverse to co-hosts Gabon.
The result has left the Mena bottom of the group, and the Frenchman, a former coach of Marseille and now a key aide of Niger head coach Harouna Doula, has warned there can be no more mistakes if they are to emerge from their debut in the tournament with any pride.
"We would've preferred to play the second game against the team that lost it's first match," Courbis told BBC Sport. "Unfortunately we've now got the complication of meeting a team that already has three points.
"But it was up to us to do better than we did against Gabon."
He added: "Before thinking about beating Tunisia, let's first think about scoring one goal and taking the first point in Niger's history.
"With those objectives, and because of those objectives, we could then think about beating Tunisia, which would be a massive achievement."
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