Arsenal forward Gabriel Jesus will undergo a scan to determine the extent of a new injury.
The attacker has been besieged by injury issues since he joined the club at the start of last season.
Jesus, who has been solid when playing, could be set for a spell out of action.
After a 2-1 win over Sevilla, in which he scored, Jesus told TNT Sports: I felt something.
Let's see. I did some tests with the physio, it looks not that big, but let's see. I have a scan, maybe tomorrow. I'm pretty sure it will be nothing."
Arsenal could also have to do without Thomas Partey for a few weeks, as he missed the Sevilla game with a new injury.