West Brom goalkeeper Ben Foster has been ruled out of Saturday's Barclays Premier League clash at Sunderland after suffering a setback in his recovery from a groin injury.
The former England international has already missed the wins over Wigan and Chelsea after undergoing minor surgery last week.
But now the problem has flared up in another part of his groin and Baggies boss Steve Clarke is unsure when the 29-year-old will be able to return to action.
Clarke said: "Ben won't be fit this week. We are thinking he's got a similar problem on the other side of the groin now.
"We will get that checked out but he definitely won't be fit for Saturday."
Asked when Foster was likely to return, Clarke said: "I don't know. I'll leave that to my medical staff and we will assess it again after the weekend."
Foster has played a key role in Albion establishing themselves in the top flight but Clarke has confidence in his replacement, Boaz Myhill.
The former Hull goalkeeper produced several fine saves during the win over Chelsea - Albion's sixth triumph in seven home games this season.
Clarke said: "Boaz waited for his chance patiently but was the consummate professional every day he came in, and his performances have shown that since getting into the side."
Midfielder Youssouf Mulumbu has also been ruled out of the trip to the Black Cats with a hamstring injury.
Clarke said: "He won't be fit this weekend but we are very hopeful he will be fit for midweek against Swansea."
Central defender Gareth McAuley is back in contention after missing the Chelsea triumph with a hamstring injury.
Albion midfielder Zoltan Gera believes the next three games - Sunderland and Swansea away and home to Stoke - will provide a stern test for the fourth-placed Baggies.
The Hungary international said: "Normally against Chelsea and the bigger clubs you have no pressure. These games coming up will be different.
"They will be a big test. But we are confident we can get results from them and I'm not surprised how well we've done. We're a massive team now."