"We are facing a change in behaviour when it comes to young players", Marotta told Corriere della Sera.
The 18-year-old shotstopper who has exploded on to the Serie A scene this season informed Milan, though his agent Mino Raiola, on Thursday that he won't be extending his contract at the San Siro beyond his current expiration in 2018.
Donnarumma featured in all 38 of Milan's league games last season, while also appearing a further three times in other competitions. For us, Donnarumma is priceless.
"Having said that, the situation is dictated by the rules and we have a right to examine all options on the transfer market". We are not selling him for now.
SunSport reported two days ago how the teen sensation has rejected a new deal at AC Milan.
Milan bigwig Massimiliano Mirabelli said: "If Ronaldo wants to leave Madrid because of his tax problems and Real want to sign Donnarumma, then we are ready to talk to [club president Florentino] Perez".
Donnarumma was given his opportunity by Milan back in 2015 and has since established himself as first choice, though angry fans have greeted the latest news with a torrent of anger and the throwing of fake wads of cash. "I am not on good terms with Mirabelli, we have very different opinions and I don't like how he's managing the club". "Naturally, the decision leaves a bitter taste in the mouth, but now we have to go forward".