Atletico Madrid will be forced to pay compensation for the signing of Gelson Martins from Sporting CP.
The 23-year-old joined the Spanish club as a free agent, despite the Portuguese club claiming they were due a transfer fee.
Martins made over 125 appearances for the Lisbon side, winning 19 caps for his country in the process.
The player himself is currently claiming £3m from his former club after several disagreements last term, which involved a player walk-out at the club.
Sporting claim Atleti will be valid to pay the €45m for the player.
Previous Sporting president Sousa Cintra has claimed: “The player’s clause was €100m and we were only going to settle for a proposal of €45m, we have made that very clear.
“Atleti thought that we would accept anything – €15m or €17m, then finally offered €20m.
“I am sure we will not lose a court case, that is what my lawyers have told me, and now it is up to the new board of the club to decide what action to take.”
Arias suffers rib injury
An injury to Santiago Arias whilst on international duty with Colombia has seen Atletico Madrid go down to just 15 fit players for the weekend game with Eibar.
The defender arrived at the Wanda Metropolitano this summer from Dutch side PSV and he had been given the chance by Diego Simeone after an injury to Juanfran.
However, he will now miss a number of games through an inflammation of the rib, suffered in Friday’s game with Venezuela.
Arias has now returned to Madrid and will not meet Argentina this week, and he now leaves Simeone with 15 players for the game against Eibar.