West Ham will be without Michail Antonio against Chelsea on Sunday and Manuel Lanzini also looks likely to miss out.
Winger Antonio will miss the rest of the season with a hamstring injury, while Lanzini is struggling with a knee problem.
Antonio will undergo an operation, Hammers manager David Moyes confirmed at a media conference on Friday.
Moyes said: “He is out for the season. He is going to have an operation on his hamstring and the biggest thing now is to get him ready for the start of next season.
“He’s a big miss, someone we need. He has great pace, great strength and we will miss him until the end of the season.
“They tell me last season he had very few injuries, but he picked up one at the end of the season with his hamstring and he’s never really recovered from that.
“In the time I’ve been here he’s had a few pretty bad injuries. It is what it is, we have to get on with it. He’s a miss to us and we hope we can get him back quickly for the start of next year.”
Lanzini, meanwhile, suffered his injury on international duty with Argentina.
“He’s back running, but he was running last week,” said Moyes.
“He’s got a medial ligament injury which is affecting his turning and twisting. I wouldn’t completely rule him out but at the moment he’s a doubt.”