PSV are seeking legal action against Zakaria Labyad for allegedly dishonouring his contract with them and signing for Sporting Lisbon.
Labyad was officially presented as a Sporting player on a five-year contract on Monday, with the Portuguese club claiming that they had signed the 19-year-old on a free transfer.
However, PSV dispute the deal struck between the Morocco international and Sporting, claiming that the midfielder is still under contract with them.
Labyad signed a three-year deal with PSV when he was 16 with the Dutch giants retaining the option to extend it by two more years.
The Eredivisie outfit later cancelled that option but stated that they wanted to negotiate a new contract. However, Labyad and his father, who is also his agent, refused to do so, pointing out that according to a Fifa rule, a 16-year-old cannot sign a five-year contract with PSV.
Nevertheless, in May PSV said that Labyad will remain with them for one more year at least, and the teenager and his father forgot to formally announce that he will leave the club in the summer as they are bound by law to do.
PSV have now lashed out at both Labyad and Sporting and are looking to take the case to court, and could put pressure on the Lisbon outfit for a transfer fee.