Monaco forward Pietro Pellegri is expected to be sidelined for a month after undergoing thigh surgery.
Head coach Leonardo Jardim believes the 17-year-old is unlikely to be fully fit again until November, although he refused to offer any guarantees.
"I don't know if it's as a result of the groin operation [in March]," Jardim told a news conference. "But the truth is he has problems.
"I don't know how long he'll be out, but an operation at this level is, in my experience, a month for sure.
"The lad doesn't have any luck. He arrived [in January] with problems and that hasn't stopped."
Monaco confirmed earlier on Friday that Pellegri had undergone surgery.
The rising Italy star – who was signed from Genoa - has only managed three Ligue 1 appearances this season due to a series of injury problems.