Subotic has been trailed by some of Europe’s top clubs in recent years, and the Serb has been crucial in the German side’s rise to the top of the Bundesliga.
Dortmund chief Hans-Joachim Watzke said: “We do not even think about selling anyone during the summer. Should there be a fantastic offer dropping in for any player and given this offer would be also of significance for Borussia Dortmund, we would still remain very much unprepared to sell.”
