Andy Carroll faces another lengthy spell on the sidelines after West Ham manager David Moyes confirmed he may require surgery.
Carroll, linked with a move to Chelsea during the transfer window, has been absent from West Ham's recent fixtures with an ankle issue.
The Hammers had hoped the 29-year-old, whose career has been scuppered by a host of injuries, would be missing for only a number of weeks.
But Moyes, speaking ahead of his side's Premier League clash against Bournemouth on Saturday, conceded that he could now be ruled out for months.
"We found out yesterday after Andy went for a scan and it showed up that he has got a problem," Moyes said. "We are not sure whether the ankle will need an operation or not.
"We are getting two or three specialists to look at it and then we will be able to make the correct decision. Hopefully we will know within a week."
Carroll has featured 14 times for the Hammers this season, and found the back of the net just twice after he netted a brace against West Brom at the beginning of the month.
"To lose him takes away a big part of our armoury," Moyes added. "It is frustrating for Andy, but it is frustrating for us.
"Andy gives us another option and alters the way other teams play against you so to lose him is certainly a big miss."
West Ham are unbeaten in their last six matches in all competitions and will host Bournemouth at the London Stadium bidding to win consecutive Premier League matches for the first time in a year.
Moyes replaced Slaven Bilic with West Ham's Premier League status in serious danger, but the former Everton and Manchester United manager has guided the east Londoners to 11th in the division.
And the Scot, who recorded his 200th Premier League victory in their 4-1 demolition of Huddersfield last weekend, believes his side need five further wins to guarantee their safety.
He added: "205 [victories] is what I am aiming for at the moment because that would mean West Ham staying in the Premier League. If I can get another five wins, then I think that would be enough to keep us up.
"All the managers in this league will be thinking there is no easy game. Everyone is difficult and there is not anything to suggest that anyone is any better than anyone else.
"I think it is going to be nip and tuck all the way. At the moment, we are on a good run and we are doing okay, but it is important to keep that going, otherwise if it goes the other way, we could be at the bottom.
"I have set no targets with the players, but 40 points was always the magic figure and the sooner you get to it, the better."