The Serie A powerhouse have appointed former Italian national team head coach Spalletti to take the helm for the remainder of the campaign.
The experienced coach takes over from the Croatian manager, who was let go post the Lazio setback recently.
Tudor had joined the club in March to replace Thiago Motta but departed after seven months after an eight-game winless streak.
Under Spalletti, Napoli clinched the Serie A championship in 2022-23 then moving on to lead the Italian national team, after the team's failure to reach the 2022 World Cup with Mancini at the helm.
Under his guidance, they made it to Euro 2024 exiting in the last 16 stage against Switzerland.
Nonetheless, Italy dismissed Spalletti in June following a loss to Norway in World Cup qualifying, putting Italy in danger of missing a third straight World Cup.
Spalletti has also managed Inter Milan, Roma and Udinese in Serie A and lifted the Russian league trophy twice while at Zenit St Petersburg.
Massimo Brambilla took interim charge of Juventus in the midweek 3-1 triumph over Udinese placing them seventh in the Serie A standings - six points behind leaders Napoli after nine games.
Their Champions League campaign sees them in 25th place in the group stage, with one loss and two draws in their first three games.