Arsenal have revealed that club captain Cesc Fabregas is set to be sidelined for two weeks with a hamstring injury.
The Gunners have also announced that Emmanuel Eboue will be missing for at least four weeks as he nurses a knee ligament problem.
Both men sustained the injuries during Tuesday's 2-0 defeat to Braga in the UEFA Champions League.
Fabregas had been carrying a problem into that contest and was forced to hobble from the field with just over 20 minutes remaining.
He was followed down the tunnel by Eboue shortly afterwards, with the versatile Ivorian stretchered off eight minutes from time.
Arsenal continue to assess the full extent of both injuries, but Arsene Wenger has admitted that the pair are set to be out of action for the foreseeable future.
"Eboue has a medial knee ligament strain," he said told Arsenal TV Online.
"It can be four weeks, can be six weeks or can be eight weeks. But I think it will be four weeks minimum.
"Fabregas will be assessed today (Thursday) with a scan. After that we can tell you how long he will be out, but I count two weeks.
"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."
Wenger has, however, received some welcome news on the injury front, with Manuel Almunia and Aaron Ramsey having made their return to action in the reserves.
Both may be forced to bide their time as they await a first-team recall, but there is an outside chance that they could be involved at Aston Villa on Saturday.
"We have a lot of bumps and bruises but everyone else should be available," said Wenger.
"Almunia should be capable to play but I will see how he reacts.
"Ramsey needs competitive games. He played 45 minutes and he did well. We need to get him slowly and progressively into competition mode."