There are conflicting reports over whether Italy will use 4-3-3 or 3-5-2 against Bulgaria, with Andrea Pirlo in doubt.
The Azzurri beat Malta 1-0 on Thursday evening and continue their Euro 2016 qualifying campaign at the Stadio Barbera in Palermo tomorrow night.
It had until now been widely reported that Coach Antonio Conte would return to a 3-5-2 system, dropping New York City FC midfielder Pirlo to the bench.
The veteran was sluggish and made numerous inaccurate passes during the Malta game.
The all-Juventus back three would be in place, with Daniele De Rossi and Roberto Soriano in midfield, Franco Vazquez partnering Graziano Pellè.
However, Sport Mediaset maintain that was only an experiment, so the 4-3-3 shape will continue against Bulgaria.
In that case, Pirlo would be started again with Marco Verratti, while Marco Parolo is the favourite to replace injured Andrea Bertolacci rather than De Rossi.
Alessandro Florenzi is expected to step in at right-back with Matteo Darmian on the left.
As for the forwards, Antonio Candreva and Eder are ahead of Simone Zaza and Lorenzo Insigne, leaving Vazquez out completely.
Italy probable (3-5-2): Buffon; Barzagli, Bonucci, Chiellini; Parolo, De Rossi, Verratti, Soriano, Darmian; Pellè, Vazquez
Italy probable (4-3-3): Buffon; Florenzi, Bonucci, Chiellini, Darmian; Parolo, Pirlo, Verratti; Candreva, Pellè, Eder
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