According to reporter Gaston Edul, Mastantono's transfer fee for joining Real Madrid will set a domestic historical record in Argentina.
The reporter said: "Mastantono will become a Real Madrid player. The contract has been finalized until 2031, with a transfer fee of 45 million euros. Real Madrid and River Plate are only discussing payment methods, and the transfer is about to be completed."
"Real Madrid requires Mastantono to join in August this year, and it is almost impossible to keep him in River Plate until December. This will become the highest transfer in Argentina's domestic football history."