West Brom manager Roy Hodgson's disappointment at defeat to Stoke compounded the news Peter Odemwingie has suffered a reaction to his ankle problem.
The striker picked up the injury in pre-season, but featured as a 75th minute substitute in the defeat at Chelsea last weekend before sitting out the 1-0 loss to Stoke on Sunday.
Hodgson has confirmed Odemwingie, who was the subject of a rejected summer bid from Wigan before signing a new three-year contract, has experienced a setback.
The West Brom boss said: "How serious it is, we don't know. He played last Saturday for 10 minutes against Chelsea, he trained Monday-Tuesday, then we had two days off.
"When we came back in, the ankle injury was plaguing him again. I'll have to wait and see. I thought on Tuesday when I left the training ground that he would be fit at the weekend.
"But his ankle isn't okay and we will have to wait and see when it will be."