Olivier Giroud had a rare opportunity to start against West Ham but was ruined when he limped off clutching his right leg during the 78th minute.
Arsene boss Arsene Wenger is also worried since Francis Coquelin was also hindered because of a cramp during their game but he is expected to be ready on Friday when they go against Liverpool.
“It looks like that. We have to wait. Nowadays you do the scan 48 hours after the injury,” Wenger said.
“That will happen on Thursday, then we will have a precise kind of grade on what his hamstring [injury] is.
“When you listen to him, the pain is quite big, but the grade is not always linked to the intensity of the pain.
“In his statement [to me], it does not look very good.”