The Serie A powerhouse have named former Italy manager Spalletti as their manager for the remainder of the campaign.
The experienced coach steps in for his predecessor, who was let go post the Lazio setback on Sunday.
Tudor arrived at the club in March to replace Thiago Motta but departed after seven months at the end of an eight-match winless run.
Under Spalletti, Napoli clinched the Serie A championship in 2022-23 prior to assuming the Italy role, which missed out on the 2022 World Cup under former boss Roberto Mancini.
He helped them qualify for Euro 2024 but were eliminated in the round of 16 by Switzerland.
Nonetheless, Italy dismissed Spalletti in June post a qualifying defeat against Norway, as Italy faced the possibility of not making a third World Cup in a row.
Spalletti's managerial career includes 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 moving them to seventh position in the league - six points adrift of Napoli at the top after nine rounds.
They are 25th in the league phase of the Champions League, having lost once and drawn twice in their opening three matches.
