Arsenal are worried that Rob Holding may miss the rest of the season as a result of the ligament injury he sustained against Manchester United.
The Daily Mail reports that the early signs coming out of the Emirates are not good for the young defender.
Holding was forced off during the 2-2 draw with Manchester United at Old Trafford on Wednesday night.
The news comes as a huge blow to Arsenal, who were just showing signs of a settled defence.
Unai Emery has tinkered with his side since joining in the summer but has found success recently after switching into a back three, with Holding playing a key role in that transition.
The latest injury news could force the Gunners boss to reevaluate his plans going forward.
Holding has impressed under Emery this season, despite it looking like he could be forced into leaving the club earlier this year.