Zorc admits they wanted the Japan international ahead of recent signing Henrikh Mkhitaryan.
"Shinji has always said that he would someday return to Dortmund. After the departure of Mario Götze was certain, of course, the first thought was, how the situation is in the case of Shinji Kagawa," said Zorc.
"But after a call, it was clear that neither the player nor Manchester United were interested at this time for a change."
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