Kalidou Koulibaly was not part of the Chelsea training session on Monday ahead of their decisive Champions League group stage clash against RB Salzburg tomorrow.
The 31-year-old missed the match against Manchester United at Stamford Bridge on Saturday due to injury and is now a doubt heading into a game that could see the Blues secure qualification to the knockout stages of the competition.
Chelsea held an open training session ahead of the match in Austria, and Koulibaly was not part of the group taking part.