West Ham will assess Marko Arnautovic after the forward injured his right foot in the disappointing 3-0 Premier League reverse at Wolves.
Arnautovic signed a new contract with West Ham shortly after Saturday's humiliating 4-2 FA Cup defeat at League One's bottom club AFC Wimbledon, ending speculation over a move to the Chinese Super League.
But the 29-year-old was withdrawn with around 15 minutes remaining at Molineux on Tuesday and was later pictured on crutches and wearing a protective boot.
"[There is no update] at this moment, but it will not be an easy injury," Hammers boss Manuel Pellegrini said.
"We must review him tomorrow [Wednesday]. It's his foot."
West Ham were fortunate to make it to half-time at 0-0, but after the break Romain Saiss' header and a fine Raul Jimenez double consigned the Hammers to a third straight loss in all competitions.
Pellegrini was at a loss to explain why his side underperformed, although he feels a hectic fixture list may have contributed.
"It was impossible to play worse. We were so not concentrated in what we did," he added.
"There are a lot of reasons for us to try and understand what is happening. The players are maybe feeling the amount of games played recently.
"I was looking for a reaction after our loss in the cup, it was the moment to do that here. We couldn't do that, we will review what we are doing because what we are doing, we are doing bad."
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