Dortmund chief executive Hans-Joachim Watzke has attempted to speed the process of Aubameyang's exit by saying the German club will not 'wait much longer' for clarity on the striker's future.
Chelsea are believed to have taken the lead to sign the Gabon international, but Dortmund's patience is running thin.
'We have told Auba [Aubameyang]: 'If you want to move somewhere, and you have a club willing to meet our demands, then come to us and we'll talk', Watzke told German publication Welt am Sonntag.
'But this will only apply within a certain time window, which is slowly closing. We would clearly need to get a replacement for him, which is difficult to impossible in any event', he said, as the German side have eyed a replacement from the Premier League.
With Diego Costa leaving the club this summer, Chelsea are in the hunt for a top-quality striker, but it seems they are going to have to hurry up if they don't want to miss out on one of their top three options.