Youssef Ait Bennasser has been ruled out of action until May with a thigh injury and faces a fight to be fully fit for Morocco's World Cup campaign.
The 21-year-old midfielder suffered the injury during his French side Caen's 3-0 defeat at Angers last month and was substituted after just 69 minutes.
"Youssef will be out for five weeks and should be ready for the Monaco match (6 May)," Caen coach Patrice Garande announced ahead of Sunday's fixture against Montpellier.
Ait Bennasser is expected to return for the last three games of Caen's Ligue 1 season and has only eight days to convince Morocco coach Herve Renard to include him in the Atlas Lions' 35-man provisional squad for Russia.
The World Cup provisional squad lists - which have increased in size from 30 to 35 players - are required to be submitted by 14 May, with a final 23-man squad list to be finalised on 4 June at the latest.
Having missed the last two international friendlies against Serbia and Uzbekistan, the France-born player, on loan at Caen from Monaco - must prove his fitness to join the Atlas Lions' World Cup campaign this summer.
Capped 11 times by Morocco, he has made 22 appearances for his loan club this season in the French top flight.
Meanwhile, Caen's injured Senegal international defender Adama Mbengue is to undergo a special two-week treatment.
The 24-year-old left-back, who made a brilliant start to the season in the first 19 matches, has been sidelined by abductor problems since January.
"With the agreement of the club, Adama consulted other doctors. If there is no solution with this treatment, we will move to an operation," Garande added.
"As a result, the season of the Senegalese left-back would be over and his dream of participating in the World Cup in Russia this summer gone."
Mbengue made four appearances for Senegal under current coach Aliou Cisse before his injury setback.