West Ham captain Jarrod Bowen will be sidelined for an extended period with a fractured left foot, the club said on Tuesday.
The England international suffered the injury during Sunday's 5-0 loss to Premier League leaders Liverpool and was substituted in the second half.
"The injury to his left foot, picked up in the first half at London Stadium, will sideline the Hammers captain heading into the New Year," West Ham said in a statement.
Bowen has been a key player for Julen Lopetegui's struggling West Ham team this season, scoring six goals in all competitions.
The 28-year-old confirmed in a post on social media that he had tried to play on after sustaining the injury.
"As always I tried to fight on and continue playing until I physically couldn't," Bowen wrote on Instagram.
"Injuries happen in football, but I'm already looking forward to getting back out there as soon as possible. See you all soon."
However, West Ham will take heart from striker Michail Antonio being discharged from hospital on Tuesday, more than three weeks after sustaining a broken leg in a car accident.
Information from Reuters contributed to this report