Chelsea manager Thomas Tuchel revealed he will be without five players for their Champions League trip to Zenit St Petersburg, including midfielder Mateo Kovacic, who tested positive for Covid-19 just one day after returning to training. Kovacic, 27, had been out of action since late October with a hamstring injury and Tuchel had hoped to ease him back into action this week. However, the Croatian returned a positive coronavirus test shortly after rejoining his teammates on the training ground and has now entered isolation. "We have bad news because Mateo was in training yesterday and with a big smile and it was a pure pleasure to have him back," Tuchel said during his pre-match press conference on Tuesday.. "But he tested positive today, for coronavirus, so he's quarantining for a few days. So it's a huge setback for him personally and for all of us." N'Golo Kante remains sidelined with a knee issue, while Jorginho has been forced to play through the pain of a back problem and will now miss Wednesday's Champions League trip to Zenit, leaving Tuchel short of central midfielders. "Jorginho is out with back pain and we played with that pain against West Ham United," Tuchel said. "He’s come from the Champions League final, the Euros and straight into the Super Cup, so we expected there to be a stage where he suffers a little with being overloaded. "We had a bit of an acute overload due to injuries and the schedule. Due to our injuries in some position, like central midfield, when we struggle. The game tomorrow is not the problem, it's more the game that comes up on the Saturday." In addition to his absent midfielders, Tuchel will also still be without central defender Trevoh Chalobah and wing-back Ben Chilwell. Chelsea, the reigning European champions, have already qualified for the knockout stages of the Champions League and will be confirmed as winners of Group H if they equal or better Juventus's result against Malmo on Wednesday.