Angelo Ogbonna has undergone surgery on his knee that is likely to rule him out for the remainder of the season.
The 33-year-old defender suffered an anterior cruciate ligament injury in West Ham's 3-2 victory over Liverpool prior to the international break.
Ogbonna appeared in discomfort early in the first half of the game at the London Stadium, he was treated by West Ham's medical team and replaced by Craig Dawson in the 22nd minute.
Following the surgery, Ogbonna took to social media to confirm the procedure "went well" and express his gratitude for supportive messages he had received.
He tweeted: "The surgery went well and now the recovery begins... I can't wait to get back on the pitch as soon as possible.
"Thank you for all your messages of support. Today, even from here, I will support the Team! Come on you Irons."
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Ogbonna started every game for David Moyes' team prior to sustaining the injury, proving integral to West Ham's strong start to the 2021/22 campaign.
The blow leaves Moyes with just three senior centre-back options in Dawson, Issa Diop and Kurt Zouma.
At Moyes' pre-match news conference ahead of Saturday's trip to Wolves, the West Ham manager said: "I think most people who know much about injuries and listening to what the doctors say… cruciate injuries can take around about nine months.
"You only need to look at Virgil van Dijk, and people of that ilk, and how long it takes to recover.
"I don't think there is a quick return. I think there is a period of recovery time that has to be taken, so I think it will be hard for Angelo to be back this season."
Italian international Ogbonna has been a mainstay in the Hammers first-team since joining from Juventus in 2015, making over 200 appearances for the club.