Chelsea midfielder N’Golo Kante has been ruled out of Tuesday’s Champions League group game at AC Milan.
Kante, 31, a World Cup winner with France, has not played since August and aggravated a hamstring injury in training.
“It’s not ideal, and certainly disappointing for both him and for us. So we have to wait and see the extent and then go from there,” said manager Graham Potter.
“We are waiting on a reaction in training, and we’re waiting for the news on that.”
Chelsea will also be without French defender Wesley Fofana, who went off injured in last week’s 3-0 win at Stamford Bridge, and is expected to be out “several weeks”.
Hakim Ziyech will also miss the Group E clash in the San Siro with a sore throat.
Brazil veteran Thiago Silva returns, having being rested for Saturday’s 3-0 Premier League win over Wolves.
“Thiago was okay when we played AC Milan but he just got a little bit worse as the week went on,” said Potter of the 38-year-old.
“Because there were only two days in between the games it made no sense to play him again. But he’s recovered well, and he’s been incredibly impressive on and off the pitch.
“As a leader, he’s a top professional, and a top person so he’s been a joy to work with.”