Portuguese side Sporting CP have filed a complaint with FIFA against goalkeeper Rui Patricio and new club Wolverhampton Wanderers, demanding €54.7m in compensation over the deal.
Portuguese publication Record released a copy of the extensive legal document, filed through the law firm of Juan de Dios Crespo Pérez, a Spanish lawyer and specialist in sports law and contract litigation.
The 30-year-old shotstopper terminated his contract at the Portuguese club, citing just cause after he and his teammates were attacked by the club's fans at a bizarre training ground incident. Subsequently, Patricio has signed for Premier League new boys Wolves.
Patricio had played for Sporting since the age of 13, joining the first team when he was 18 - back in 2006. During his time with the club, he made 327 league appearances.
According to the legal documents, Sporting arrived at the €54.7m fee they are pursuing due to an agreement by both parties involved - Sporting and representatives for Patricio - that the player's market value stands at €45m.
Added to this was then the remaining value of the player's contract at Sporting, which stands at €9.7m - totaling up to the sum the Portuguese club are pursuing against Patricio and Wolves.
There is past legal precedent for Sporting's claims too. One of the case law examples that Sporting point to in the document relates to Australian footballer Mark Bresciano and his controversial 2012 move from UAE side Al-Nasr to Qatari team Al-Gharafa.
In that instance, it was ruled that Bresciano unilaterally breached the contract he had with Al-Nasr in order to finalise the transfer - the same action Sporting are arguing Patricio has done to their club.
Bresciano was suspended for four months and fined €1.37m for the incident. While a ban is unlikely in Patricio's case, it does mean that there is legal precedent to strengthen Sporting's financial pursuits in the claim.
That could mean a significant financial outlay in the near future for Wolves, who may very well see a summer free transfer quickly become the club's most expensive transfer dealing.
Patricio had already been close to agreeing an €18m move to Wolves from Sporting prior to the training ground incident and the termination of the goalkeeper's contract - further adding to the Portuguese side's feeling that they lost out on valuable money.