Kai Havertz is a doubt for Chelsea to face Tottenham Hotspur in the Premier League on Thursday night.
Chelsea make the short trip across the capital to face Jose Mourinho's side looking to extend their unbeaten run under Thomas Tuchel to three games.
And Havertz, who was likely to start against Spurs, is a major doubt for the Blues handing Tuchel a blow ahead of his first London derby.
During training on Wednesday, the 21-year-old had to withdraw after picking up a slight issue.
Tuchel revealed: "We had two little issues today on the training pitch. It was Kurt Zouma and Kai Havertz who went off the pitch with little issues so they are checking issues and doing images right now. It is questionable if they are in the squad for [Thursday]."
Zouma is also a doubt for the Blues, however he's not featured for the Blues under Tuchel yet which could see Antonio Rudiger, Thiago Silva and Cesar Azpilicueta line up at the back once again.
Hakim Ziyech will return for the Blues after missing the 2-0 win over Burnley.
Tuchel will have a fully fit squad apart from the possible duo being unavailable and he is unlikely to risk the pair.
The 47-year-old is extremely happy with all of his squad: "I’m not surprised [with the quality of the squad] and I am delighted with the way we train and behave. We can be flexible because there are two or three who can play the positions at a high level. I am absolutely pleased with the behaviour and atmosphere we have right now.
"We have to keep on going because this is exactly how it should be to grow as a team."