Chelsea midfielder Mateo Kovacic has tested positive for Covid-19 - just a day after returning to full training following an eight-game layoff with a hamstring injury.
The news was confirmed by Chelsea manager Thomas Tuchel ahead of Wednesday's Champions League clash with Zenit St Petersburg, with the Blues attempting to secure top spot in Group H.
Kovacic did not make the trip to Russia and will now have to self-isolate for 10 days in accordance with government guidelines.
The Croatian international - who has not played since the Carabao Cup win over Southampton on October 26 - also stands to miss Saturday's visit of Leeds to Stamford Bridge and the meeting with Everton on December 16.
Chelsea then travel to Wolves on December 19 before a Carabao Cup quarter-final against Brentford on December 22 and a Boxing Day trip to Aston Villa.
Tuchel said: “He was in training yesterday with a big smile, but then he tested positive for corona today so is now isolating.
“I was aware that this could happen and I’m not happy about it, not only as a manager, but as a person. But this is what reality is at the moment so we have to be ready to adapt and secure people’s health.”
Kovacic’s latest setback compounds Tuchel’s ongoing midfield woes amid a slump in form that has seen them slip to third in the Premier League table, with no date set for N’Golo Kante’s return from a knee injury and Jorginho also ruled out of the Zenit game.
Chelsea will also be without Trevoh Chalobah and long-term absentee Ben Chilwell at Saint Petersburg Stadium, though Kai Havertz is back in training after an ankle injury that forced him off at half-time of Saturday’s London derby defeat at West Ham.
