Arsenal fear Rob Holding could miss the rest of the season with a cruciate ligament injury.
The centre-back was forced off on a stretcher in the Gunners’ 2-2 draw with Manchester United on Wednesday, following a challenge with Marcus Rashford.
Arsenal are yet to confirm the extent of the knee injury sustained by the Englishman, but there are genuine fears he could have damaged his cruciate.
Holding is being assessed by Gunners medics following the injury. Emery said on Thursday: “The first news is not good.”
Midfielder Aaron Ramsey (ankle) will be monitored before Saturday’s Premier League clash with Huddersfield, which Mesut Ozil is expected to miss with a back problem.
Emery added: “He had back ache and now he’s working with one physio. We’re going to look when he can come with us.”
Laurent Koscielny could come into the squad, after twice playing for Arsenal Under-23s, either on Saturday or next week against Qarabag in the Europa League.
Emery said: “The 18 can be for Saturday and also we are doing one plan with him, maybe he can play against Qarabag.
“He’s working with us every day in training and playing in the under-23s with good feeling. The next step, I think, is with us.”