Chelsea captain Reece James sustained a hamstring injury in Sunday's Premier League defeat to Everton.
James, 24, has struggled with injuries over the past two seasons, featuring in only 24 Premier League games since the start of the 2022-23 campaign.
"Scan results have confirmed a hamstring injury," the club confirmed.
"Reece [James] will now begin his rehabilitation programme at Cobham."
The Blues are yet to confirm how long academy graduate James will be sidelined for as they prepare for a busy schedule over the festive period with five games on the horizon before the end of the year.