Arsenal have reportedly been rocked by the news midfielder Mohamed Elneny sustained a long-term hamstring injury in Saturday's 2-1 win against Fulham.
The Egypt midfielder made his first appearance of the season at the weekend and played the full 90 minutes as the Premier League leaders made it four wins from four this season.
He replaced Thomas Partey - who missed out due to a tight right thigh - in Mikel Arteta's starting XI as they came from a goal down at Emirates Stadium to retain their unblemished start to the campaign.