Arsenal lost centre-back Laurent Koscielny to an apparent head injury early during their Premier League clash with Leicester City, as the French international got the worse end of a clash with Jeffrey Schlupp.
The experienced defender received extensive treatment on the pitch, but he didn't look well at all, as shared by Sky Sports News:
The treatment continued in the tunnel as Arsenal were hesitant to go for an immediate substitute, and Koscielny returned to the field wearing a protective wrap on his head (via Football Tweet):
However, Koscielny was clearly out of sorts and lost his positioning when Leicester scored, prompting Arsene Wenger to bring on Calum Chambers, via the club's Twitter feed:
Further testing will have to be done, but the Frenchman may have suffered a concussion that could keep him away from the pitch for significant time.