NAPLES, Italy — Napoli forward Arkadiusz Milik will again be sidelined for about four months after another knee injury.

Milik had an operation in Rome on Monday after injuring his right knee in Saturday’s 3-2 victory over Spal.

The Poland international missed four months of last season after damaging ligaments in his left knee on World Cup duty.

Napoli says it is not “an isolated injury but a complex one,” adding “the surgery was perfectly successful.”

The club says Milik’s recovery time will be “similar to that of his previous injury.”

The 23-year-old Milik scored in Napoli’s opening match, a 3-1 victory at Hellas Verona, and also converted a penalty in its Champions League loss to Shakhtar Donetsk.

Before his injury last season, Milik scored seven goals for Napoli after joining from Ajax.