Atletico Madrid have taken legal action against Barcelona over their deal for Antoine Griezmann.
Atletico have been arguing that Barca struck terms with the Frenchman before his buyout clause fell from 200m to 120m.
And El Mundo says the Madrid giants have now acted, amid claims they have correspondence between the player's lawyer and family members detailing the terms of the transfer.
It's suggested the timestamp is proof that negotiations were being carried out while Griezmann's buyout clause was still 200m.
The fresh development could now force Barca to cough up the extra 80m Atletico believe they are owed given the timing of the move.
