Barcelona are to sue former player Neymar for 8.5m euros (£7.8m) over his 222m euro (£200m) world record move to Paris St-Germain.
The Brazil international made the move to the French club in August after buying out his contract.
The Catalan club are now claiming a breach of contract by Neymar as he only signed a new five-year deal in October.
The Spanish club say they are seeking “8.5m euros (£7.8m) in damages, and an additional 10% in interest”.
The club’s claim relates to a bonus payment Neymar received when agreeing his new deal last year.
Barcelona said in a statement the club “decided to take these actions in defence of their interests”.
Neymar criticised the directors of the club on Sunday after scoring twice on his home debut for PSG in a 6-2 win over Toulouse.
“I spent four beautiful years there and parted happy,” said the 25-year-old. “But with [the board], no.
“For me, they are not the people who should be there, for the direction of Barca. Barca deserve much better.”