Borussia Dortmund chief Michael Zorc admits it's frustrating seeing their best players constantly linked with Europe's biggest clubs.

Dortmund have attempted to deter interest in their key men but have been unable to say with any certainty that they will stay put and Zorc has spoken out over the issue.

Zorc said: "It would seem that we constantly have 17 players on the verge of moving to Real Madrid or Manchester United.

"We have been putting up with this kind of rumours on a weekly basis for the past 4 years now.

"But this at least confirms that we are working well."