Koulibaly, 31, has established himself as a crucial part of new manager Graham Potter's plans since arriving from Napoli for £34 million earlier this summer. He has made 11 appearances across all competitions for the west London outfit so far, with five coming under Potter.
A right-footed ball-playing centre-back, Koulibaly missed his team's thrilling 1-1 Premier League draw against Manchester United at Stamford Bridge on Saturday (22 October) due to a knee injury.
Speaking at a press conference, Potter provided an update on the Senegalese's recent injury. He told reporters (via Football London):
"He just felt his knee at the back end of the game against Brentford. It's not too bad but it's too soon for him to play in this game. We lost Koulibaly, so we can't play him"
As per The Evening Standard, Koulibaly is set to be ruled out for Chelsea's trip to Salzburg on Tuesday. The former KRC Genk man missed his team's final training session at Cobham ahead of the Champions League clash.
Apart from Koulibaly, the Blues are currently without the services of Wesley Fofana due to a knee problem. Thiago Silva and Trevoh Chalobah are the only available centre-backs for the club.
Meanwhile, Reece James and N'Golo Kante are also sidelined with knee and hamstring injuries, respectively. Both players have been ruled out of the 2022 FIFA World Cup.
While James is expected to return to action in December, Kante is said to be available again next year.
Richard Keys expresses doubts about Chelsea under Graham Potter
On his personal blog, former Sky Sports presenter Richard Keys raised concerns over Potter's personality after Chelsea's recent Premier League stalemate against Manchester United. He wrote:
"There's another nice guy at Chelsea and I've got all the same doubts about his personality that I had about [Eddie] Howe's. There's no 'devil' in Chelsea anymore."
"They're neat and tidy – they're a big Brighton really. They'll win more than they lose – many more – but I don't see them putting big games to bed with the same efficiency that they once did."
Potter has been in charge of the Blues for eight matches, boasting a record of five wins and three draws across all competitions. So far, his team has scored 14 times, conceding only three goals.