Chelsea boss Mauricio Pochettino admits losing Reece James is a blow.
The new club captain has suffered a fresh hamstring injury, which could see him sidelined for months.
Pochettino said, "It's a sad moment because he is our captain and he was so excited to be a captain and he was full of energy.
"We are going to asses him day by day and as soon as possible we want him again with the team.
"For sure he's going to become stronger than he was because we are going to help him to become stronger than before."