The 23-year-old made his return to the starting line-up in Saturday’s 2-0 win over Chelsea after a month out with a calf injury but went down clutching his knee after overstretching to regain possession.
Bellerin appeared distraught and lay in agony as he received treatment and was eventually stretched off with 20 minutes left to play.
The Arsenal medical team are assessing the injury and fear the Spaniard could have suffered ACL damage. If this appears to be the extent of the injury, then he could be ruled out of action for the remainder of the season.
Arsenal are already short of options in defence as it is, so the news will come as a blow to Unai Emery.
Speaking after the game, Emery gave his assessment of the injury sustained by Bellerin:
“It is his knee and the first prediction is it is an important [bad] injury.
“We have to wait until tomorrow, but first impressions are not positive.”
It is unlikely that the Gunners will look to sign a replacement for Bellerin this month as Emery has no money to spend and already has the likes of Ainsley Maitland-Niles and Stephan Lichtsteiner to step in for the stricken full-back.