Tuchel insists he'd like the Dane to sign a new deal and stay with the Blues.
He said of his Bosman prospect today: "We hear the rumours with Andreas and it's been like this for many months.
"He has not signed yet so we can't communicate anything. We are not happy about it and personally and the club representatives think it's best for him to stay here. We rely heavily on him.
"We have to consider the possibility that he may leave us. Will we like that? No. Will we live with it? Yes.
"If things happen, it's normally the best thing not to take them personally. He is still our player and we will do what is best for us while he is a Chelsea player.
"He knows we appreciate him a lot and I think it's a crucial point in his Chelsea career; he is in a perfect age and perfect moment with the system we play and the guys at his side.
"I think it's the decisive moment to step up and be a huge player for Chelsea in the next years. If he decides otherwise, I will not take it personally."