Arsene Wenger is hoping Cesc Fabregas will only be out for two weeks with the hamstring injury suffered in Arsenal's Champions League defeat at Braga.
Gunners captain Fabregas is set to undergo a scan to determine precisely how long he will be sidelined for but manager Wenger is optimistic it will be a short hiatus.
However, Wenger hinted Fabregas - who has had real problems with the hamstring in his other leg this season - might need to have his game time rationed when he returns.
The Gunners boss added: "It is a big blow because it will question how cautious we have to be in the future with him.
"Cesc has played 50 games a year since a young age.
"We may have to be more cautious with him, especially in the next two months."
Fellow midfielder Emmanuel Eboue, who was carried off on a stretcher in Portugal on Tuesday night, faces between four and eight weeks out with a knee ligament strain.
Wenger said: "It can be four weeks, can be six weeks or can be eight weeks. But I think it will be four weeks minimum."