Takehiro Tomiyasu was forced off through injury against Newcastle on Monday night.
The Japanese international has had his fair share of injuries since joining the Gunners last summer and his season could now be over after he left the field in agony in the first-half on Tyneside.
Tomiyasu appeared to be experiencing some pain in his hamstring, an injury that has caused him a relative amount of trouble this campaign. Cedric Soares came on at right-back to replace him, but the injury is a serious worry for Mikel Arteta as he looks to secure Champions League football at Arsenal for the first time in five years.