Chelsea have arrived in Italy ahead of facing AC Milan in the Champions League second leg match.
Graham Potter has revealed that N’Golo Kante has suffered a reaction in training that must be assessed.
The Frenchman misses Chelsea’s match against AC Milan on Tuesday night.
Hakim Ziyech will also miss the trip to the San Siro as he misses the game through illness.
Kante, Ziyech and Wesley Fofana were the first team players not to travel to Italy ahead of the game against AC Milan, with none of the trio involved in training at Cobham early on Monday
Fofana is set to miss a number of weeks of football, having strained his knee in Chelsea’s Stamford Bridge clash against the Serie A side.
The Blues are waiting to discover the extent of Kante’s setback, with Potter admitting it is not an ideal situation.
The Chelsea head coach said: “Hakim is ill, N’Golo we’re just waiting. He had a reaction in training, so we’re just waiting for the news on that. Hakim has a sore throat, that’s why he didn’t travel.
“It’s not ideal [Kante’s issue] and disappointing for him and for us, so we have to wait and see the extent of it and then go from there.”
He added: “Everyone is available apart from the guys we’ve mentioned. The fact we could rotate a few has probably helped us in terms of availability for this game and, hopefully, a bit of freshness because we’re going to need that. It’s going to be a tough match, a really physically demanding game.”