Ronald Koeman says Matthijs de Ligt needs to adapt to a new way of defending with Juventus.
The centre-back joined the Serie A champions in July for an initial fee of €75million after a standout season with Champions League semi-finalists Ajax.
He endured a tough debut in Italy's top flight in Juve's dramatic 4-3 win over Napoli but has shown some encouraging signs of a blossoming partnership with Leonardo Bonucci in recent weeks.
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Koeman thinks the 20-year-old still needs to take lessons from the "Italian school" of defending, but the Netherlands boss is not surprised to see a player so young still have room for improvement.