The veteran striker realised a lifelong dream when he made Juve the 13th club of a well-travelled career in 2011, but the 35-year-old has only bad memories of his brief spell in Turin.
The Bianconeri must avoid defeat to Fiorentina on Saturday night to avoid Napoli joining them at the top of the table with a win over third-placed Lazio and there is no doubt where Toni's loyalties lie.
He told the Corriere dello Sport: "I was a Juventus fan from a young age but when I moved to Modena I just started supporting the team I was playing for.
"What happened in Turin? I injured myself during my second game for the club and (Luigi) Del Neri told me not to give up. But then (Antonio) Conte arrived and told me to pack my bags."
Napoli can open a nine-point gap on Lazio with victory at the Stadio Olimpico with club president Aurelio De Laurentiis banishing any thoughts of a crucial home clash with Juve on March 1.
He said: "I won't talk about the Juve game. I'm superstitious before we face Lazio."
The Biancocelesti have signed former Sunderland striker Louis Saha as cover for Germany international Miroslav Klose, who will miss eight weeks through injury.
"I'm really happy to have joined this great club and to have accepted this opportunity," the Frenchman said. "I want to do my best so we can win as much as possible."
Cagliari will host a resurgent AC Milan side at Turin's Stadio Olimpico after their own Stadio Is Arenas failed safety checks, while under pressure Inter Milan boss Andrea Stramaccioni searches for an elusive win at the expense of Chievo.
Alberto Malesani has been tasked with lifting Palermo off the foot of the table after replacing Gian Piero Gasperini this week but the Sicilians' opponents, Pescara, are just as eager to escape the relegation zone.
There was a managerial change at Roma, too, where Aurelio Andreazzoli has taken over from Zdenek Zeman until the end of the season. His first task is a trip to Liguria to face mid-table outfit Sampdoria.
Parma look for a first win in five games as Samp's city rivals Genoa visit the Stadio Ennio Tardini, with the Rossoblu a much-improved prospect under returning boss Davide Ballardini.
Torino will hope to extend a seven-game unbeaten run at Udinese, where they have not won in over 20 years, as struggling Siena strive for a second win on the bounce at the expense of Bologna.
Elsewhere, Atalanta take on upwardly-mobile Catania at the Stadio Atleti Azzurri d'Italia.