Mowbray told the club's official website: "His injury didn't clear up as quickly as we thought, I'm sure it's only going to be a matter of days though."
If the former Sunderland man fails to recover in time, Mowbray is expected to name Beattie alongside Ishmael Miller in attack again. Hungary international Zoltan Gera could be in contention for a starting place, while defenders Neil Clement (knee) and Bostjan Cesar (back) remain sidelined. The Baggies will be desperate to get back to winning ways after being held at home by the Potters and in turn losing their 100% home record.