Stuttgart president Erwin Staudt has blasted Horst Heldt ahead of his impending defection to Bundesliga rivals Schalke.
Heldt wants to leave his position as the club's director of sport to link up with former mentor Felix Magath at the Royal Blues.
But Staudt, speaking from the club's training camp in St Moritz, is furious at Heldt's behaviour.
"This is the deepest disappointment of my seven years in office," he said.
"When I heard about it, I was furious. The whole board is angered."
Staudt was particularly upset to hear Heldt's reason for wanting to leave after he cited a lack of support from board level as his main gripe.
Staudt added: "I have never had a bad word to say about him. When you work in such an exposed position, you have got to live with much criticism and little praise.
"It has been the same for me."
He is now resigned to losing Heldt, who has requested that his contract, which runs until 2013, be terminated to allow the move.
But Staudt insists he will not be held to ransom by Schalke, who are not willing to pay a penny to Stuttgart to acquire his services.
"It is now up to them - they want something from us after all," he warned.