Milan announced that third-choice goalkeeper Alessandro Plizzari will be out for three months after knee surgery.
The 21-year-old spent last season on loan at Reggina, while he also had spells at Livorno and Ternana.
He has two caps for Italy at Under-21 level and was a regular for the Under-20 side.
“AC Milan can confirm that Alessandro Plizzari underwent surgery today to deal with bilateral patellar tendonitis,” read the statement.
“The operation, which was completed by the Club’s consultant orthopaedist Roberto Pozzoni at the Clinica La Madonnina under the supervision of Club doctor Lucio Genesio, was a complete success.
“His recovery time is estimated to be three months.”
Plizzari is third choice at Milan behind Mike Maignan and Ciprian Tatarusanu.