Juventus had not conceded five goals in a single competitive match in almost 30 years, but were humiliated by Napoli at the Stadio Diego Armando Maradona.
The Partenopei ran riot against a side that had kept eight consecutive clean sheets in Serie A, winning all of those games, but the Bianconeri fell apart in Naples.
Victor Osimhen bagged a brace, with goals from Kvicha Kvaratskhelia, Amir Rrahmani and Eljif Elmas, while Angel Di Maria got one back.
Juventus had not conceded five goals in any tournament since a 5-1 defeat to Pescara in Serie A on May 30, 1993.
Curiously, the first Pescara goal that night was scored by current Juventus coach Max Allegri.