Chelsea's Kalidou Koulibaly is reportedly expected to miss the Champions League group game with Red Bull Salzburg on Tuesday night due to injury.
The Senegalese international sat out the 1-1 draw with Manchester United over the weekend with a knee injury and was missing from the open training session today.
Having already seen Reece James and N'Golo Kante suffer long-term injuries, as well as defender Wesley Fofana, the Blues have seen their defensive reinforcements depleted.
Koulibaly has been a regular fixture in the Chelsea side since Graham Potter arrived at the club.
The 31-year-old has managed five clean sheets in five games under Potter and has played the second-most minutes of any Chelsea defender so far this season, behind only Thiago Silva.
However, towards the end of the 0-0 draw with Brentford, he felt a twinge in the back of his knee and was subsequently left out of the United game as a precaution.
Chelsea head into the game with the Austrian side knowing a win will secure qualification to the knockout stages as they currently sit top of Group E.
The Blues bounced back from a disappointing start to their European campaign which saw a 1-0 loss away at Dinamo Zagreb followed by a 1-1 draw at home against Salzburg in Potter's first game in charge of the club.
However, back-to-back wins over AC Milan have since seen them take control of the group.
