Just 24 hours after his return to Chelsea training, Mateo Kovacic has been forced into isolation after testing positive for Covid-19, while Jorginho will also miss the game against Zenit in the Champions League.
The Croatian missed eight games with a hamstring injury but was back in training on Monday, with a return against Leeds United at the weekend looking likely.
Unfortunately, that will not come to fruition after Thomas Tuchel revealed that Kovacic has tested positive and is no longer eligible for the game.
"Mateo was in training yesterday with a big smile and it was a pure pleasure to have him back, but he tested positive today and is isolating, so he's out for several days," Tuchel told his pre-match press conference. "It's a huge setback both for him and for us."
Jorginho, who has been nursing a niggle for a period of time, has also been ruled out with a hip injury, while N'Golo Kante remains sidelined with another knee injury.
Tuchel was asked whether Kante's sketchy injury record has anything to do with the fact that the Frenchman is now 30 years old, but the boss insisted he simply has bad luck.
"I have an open relationship with him, he takes care of himself and needs his time," Tuchel said. "We don't have the feeling that it is because of his age that he takes longer. He's a careful person and doesn't want to take risks.
"He is superman, the guy who makes the difference, the guy everybody in the world wants to have in their midfield. We miss him, but can we produce results without N'Golo? Yep, but it's easier with him. We built him up after his last injury, but he had an accident which is not related to age or overload, against Juventus. We miss him a lot."
With Kovacic, Jorginho and Kante all out, it's likely that Atletico Madrid loanee Saul Niguez will be drafted back in for another chance to prove himself after a string of underwhelming showings following his move to Chelsea.
"He's one of the guys who needs rhythm and minutes," Tuchel said of Saul. "He's always in our thoughts, we reflect on every training session and performance.
"I think he struggled a bit with the intensity, and I also think he was a bit unlikely. He played against Aston Villa, Southampton and Watford, all three were high-intensity games, above average. That does not suit his main qualities.
"We try to encourage him because he grows into Chelsea more and more. We will not stop encouraging him and trying to bring out the best, helping him to help us. It's a high possibility he will prove it tomorrow."