Edouard Mendy and N'Golo Kante will miss Chelsea's Champions League clash with RB Salzburg on Wednesday.
Graham Potter will take charge of his first game as Chelsea manager.
But the Englishman will be without Mendy and Kante due to injury.
"Edouard Mendy will miss the game, and so will N'Golo Kante," Potter said. "Both of them are progressing well but the game comes too soon.
"He [Mendy] has responded well but his knee has been bothering him for a bit. It might not be too long but at the moment he is not available."