Chelsea are sweating on the fitness of Reece James after the defender was substituted inside half an hour in the defeat to Man City at Stamford Bridge on Saturday.
James appeared to pick up the injury after just ten minutes, coming off worse despite winning a 50-50 challenge with England teammate Jack Grealish and receiving treatment on his ankle.
However, having attempted to play on he was withdrawn 20 minutes later and replaced by centre-back Thiago Silva, with Cesar Azpilicueta moving into the wing-back role in James' place.
Chelsea head coach Thomas Tuchel said after the match that James had 'twisted' his ankle, although several viewers speculated that he had in fact sprained it and therefore faced a lengthy spell on the sidelines.
Goal report that the 21-year-old left the stadium with the injury wrapped in bandaging.
Speaking in his post-match press conference following the 1-0 loss, Tuchel said: "I don’t know about Reece at the moment. He twisted his ankle and it was very painful for him.
"I have no other news on him at this stage but let’s see how he is in the next few days."
Premier League injury analyst Ben Dinnery suggested it was a strain, tweeting: "High ankle sprain for Reece James. As always, severity is key and will determine potential RTP," and adding that the average recovery time was 56 days - or eight weeks.
Chelsea will hope that is not the case, but it seems James is almost certain to miss the Champions League Group H encounter with Juventus in Turin on Wednesday. The Blues then host Southampton in west London before the international break.
England boss Gareth Southgate will also be closely monitoring the situation, with the Three Lions set to face Andorra and Hungary in 2022 World Cup qualifying in October.