Kylian Mbappé has left French Paris Saint-Germain for Spanish Real Madrid.
But the football star still has unsettled affairs with PSG.
The club owes Mbappé over 600 million kronor.
The money in question is the 25-year-old's last three monthly salaries and the final payment of a sign-on bonus that would have reached Mbappé's account in February.
The newly minted Real Madrid player has tried to get his money from PSG in recent months.
To now increase the pressure on the club, Mbappé has turned to Ligue 1's legal department and the European Football Association (Uefa). This is reported by the French newspaper Le Monde.
Mbappé left PSG after six years at the club, and joined Real Madrid on a free transfer.