The defender was forced off during Sunday's draw with Manchester United.
Emery said: "I don’t know exactly. I think it is hamstring, but I don’t know if it’s a big or small injury. Hopefully it is a small injury. We have to rest now and recover some players like Ramsey, Onana and McGinn.
"They are coming back for the next two weeks starting with us and being available to include in the squad Kamara and Tyrone Mings. Buendia is getting fitter and better. We will need them.
"We are not having a lot of important injuries, just small injuries. It is normal and some players have hamstring or small injuries. But for me it is not really relevant. The idea is to try and reduce the risk and have players to play instead of them.
"At the moment we are doing that and some players are coming back after long injuries. Players with small injuries, they should be available again like Onana and Ramsey."