The Finland under-21 midfielder is set to join the Bianconeri in January.
Mattila has been labeled as the new Ballack by the press.
It is expected that the 19-year-old will sign a five-year contract with the Bianconeri.
The Finland under-21 midfielder is set to join the Bianconeri in January.
Mattila has been labeled as the new Ballack by the press.
It is expected that the 19-year-old will sign a five-year contract with the Bianconeri.
