Sheffield Wednesday have reported Newcastle to the Premier League over the appointment of Steve Bruce as manager.
The former Sunderland boss resigned as Wednesday manager last week - before taking over at Newcastle on a three-year contract.
Bruce also took coaches Steve Agnew and Stephen Clemence with him to St James' Park.
Wednesday's season gets underway in ten days time and they've yet to appoint a replacement.
In a statement, the Owls said: "Following Newcastle United's announcement on 17 July 2019 of its appointment of former Sheffield Wednesday staff Steve Bruce, Steve Agnew and Stephen Clemence, the club confirms that it has today reported Newcastle United's conduct to the Premier League.
"As the Premier League will now initiate and carry out investigations into the club's allegations, the club will not be commenting further on this matter whilst such investigations are ongoing."
Newcastle fans have criticised the former Manchester United captain's appointment but he says it was impossible to turn down the manager's job at his boyhood club.
“Through all of this, I just thought I’ve got to go and have a crack, that was my over riding thought. No matter how difficult, no matter how much s*** I’m going to have to deal with, I had to have a crack at it.
“I honestly think whoever came in to replace Rafa, they were going to be big shoes to fill. I’m under no illusions, he is very, very talented, he is very, very good at what he does.
“I can’t take that personally, the only thing that can improve it is results. The atmosphere in the city is a result of Rafa leaving. There is naturally disappointment that the club have lost a very talented manager, but I can’t change that. We aren’t all Champions League winners, but I will do my utmost to keep the club going forward.”
The Premier League will now investigate.
