Zorc has ruled out Sancho leaving the club in the January transfer window, as Chelsea place him at the top of their shopping list.
Reports claim Sancho is unsettled at Dortmund but the Bundesliga club's director of sport insists no exit is forthcoming.
He said: “We're continuing to plan with him. He's a fundamental player for us and I do not see any scenario where he leaves us.
“We have already had some situations with him to talk about, and there have been a lot of interviews in the last few weeks.
“We are in a good way; when he came off the bench in Barcelona and also in Berlin, he gave us a top performance."