Craig Brown has quit as manager of Motherwell, just 24 hours after committing his future to the Scottish Premier League side.
Brown was approached by Aberdeen over the possibility of him taking the vacant manager's position at the club and having initially pledged his allegiance to Motherwell, he tendered his resignation.
He is now expected to take over at Aberdeen in time for the clash against Hearts on Saturday, but Motherwell have reported the club to the Scottish Premier League.
"We are surprised and disappointed by the decision of our management team to leave the club at this time and in this way," a Motherwell statement read.
"But it is not in our ethos as a club to stand in anyone's way that wanted to be somewhere else.
"We also have far too much respect for Craig and Archie and what they have achieved in the game to do anything other than wish them happiness in what they are setting out to do and to thank them for their efforts in the last year.
"It is very difficult to understand their decision but we must respect it."
The statement went on: "Separately we do wish to make clear that as a Board we believe that the conduct of the board of Aberdeen in this matter has been wholly inappropriate and in clear breach of SPL rules as well as basic courtesy.
"At no point did they inform us or seek our permission to speak to critical employees of our club and to seek to entice them to leave our employment."