Manchester United winger Bebe has been ruled out of action with a torn anterior cruciate ligament and is likely to be on the sidelines until February.
Bebe suffered the knee injury while playing for the Portugal Under-21 side in Slovakia on Tuesday night and it means he will now be unavailable for most of this loan spell with Turkish side Besiktas.
The 21-year-old was loaned to Besiktas earlier in the summer with a view to a permanent move and the news will hamper the player's hopes of earning a full transfer.
Besiktas club doctor Devrim Uygun said in a statement: "A scan has shown an anterior cruciate ligament tear to his left knee and he will be unable to play for six months.
"Surgery is required and we have contacted Manchester United and there will be a joint decision about where the operation will be done.''
United may take the decision to cancel the loan and bring him back to Old Trafford for his operation and rehabilitation.