AC Milan say they have been left with a "bitter taste in the mouth" after teenage goalkeeper Gianluigi Donnarumma turned down a new contract.
The Italy keeper, 18, now looks likely to leave the club.
Rossoneri chief executive Marco Fassone said the player had made a "definitive decision" not to renew his deal.
"We were taken by surprise, as we had hoped Donnarumma would be the goalkeeper taking Milan into the future," he added.
"Naturally, the decision leaves a bitter taste in the mouth, but now we have to go forward."
Donnarumma - whose contract expires next year - broke into the first team as a 16-year-old and has played almost 70 times since.
The player is represented by agent Mino Raiola, who last summer brokered the deal that took Juventus midfielder Paul Pogba to Manchester United for a world-record fee.
"Raiola informed us that Donnarumma has made a definitive decision not to renew the contract with Milan," Fassone said.