Veteran striker Eric Maxim Choupo-Moting and in-form midfielder Andre-Frank Zambo Anguissa have been ruled out of the match in Rabat, where Cameroon are looking to keep alive their World Cup hopes.
Goalkeeper Andre Onana is also a doubt after suffering an ankle injury, football federation officials added.
Choupo-Moting has suffered a knee sprain while Zambo Anguissa pulled out of Tuesday’s training session with a hamstring injury. The midfielder, who turns 30 on Sunday, has scored four goals for Napoli in Serie A this season.
Cameroon are participating in a playoff tournament for the four best runners-up across the nine African World Cup qualifying groups, which concluded their fixtures last month.
This week's mini-tournament offers the possibility of a 10th representative for the continent at next year’s World Cup in Canada, Mexico and the US.
If Cameroon win on Thursday, they would progress to a final in Rabat on Sunday against either Gabon or Nigeria to determine the African side that advances to the intercontinental playoff in March, where the last places for the 48-team World Cup will be determined.
Cameroon's Indomitable Lions have competed in eight previous World Cups - more than any other African nation.