Milan named their squad for the US tour, including Carlos Bacca and Suso, but Gianluca Lapadula misses out.
The new signing from Pescara was unable to take part after sustaining an ankle injury, so he will remain in Milan for treatment and specific training exercises.
It is possible Lapadula will meet up with his new teammates in the States on August 5.
Midfielder Jose Mauro is out of action following an injury.
The Rossoneri are due to face Bayern Munich on July 28, Liverpool on July 31 and Chelsea on August 4.
Bacca is included, despite being at the centre of transfer speculation with West Ham United and Arsenal.
Diego Lopez also makes the trip, although his move to Chelsea was believed to be imminent.
Milan squad for US tour: Abate, Antonelli, Bacca, Bertolacci, Bonaventura, Calabria, De Sciglio, Donnarumma, Ely, Gabriel, Honda, Kucka, Livieri, Luiz Adriano, Diego Lopez, Matri, Menez, Montolivo, Niang, Paletta, Poli, Romagnoli, Suso, Vergara, De Santis, El Hilali, Vido, Zanellato