To reach the last eight Italy must beat the Bulgarians, who have already been eliminated, and hope the game between Denmark and Sweden does not end in a 2-2 draw or higher.
Despite days of Italian insinuation about the possibility of a plot for the Scandinavian derby to end in a result that would guarantee Italy's exit, Buffon said the players did not want to know any news from the other match in Porto.
"We have to think about our game and nothing else," Buffon told reporters, "Having headsets on the bench and knowing what was happening elsewhere would only harm our performance."
Italy's preparations have been hampered by suspensions and injuries that could see six first-team players missing.
Forward Francesco Totti, midfielder Gennaro Gattuso and captain and centre-half Fabio Cannavaro are all suspended.
Coach Giovanni Trapattoni must also wait for late fitness tests on striker Christian Vieri (knee) and midfielder Simone Perrotta (calf). Cristiano Zanetti (thigh) is very doubtful.
Marco Materazzi looks the favourite to take over from Cannavaro at the back.
Bulgaria, who lost 5-0 to Sweden and 2-0 to Denmark, will be without captain Stilian Petrov, sent off against the Danes, and experienced defender Rosen Kirilov, who has two bookings.
Italy (4-3-3): 1-Gianluigi Buffon; 2-Christian Panucci, 13-Alessandro Nesta, 23-Marco Materazzi (or 6-Matteo Ferrari), 19-Gianluca Zambrotta; 14-Stefano Fiore (or 16-Mauro Camoranesi), 21-Andrea Pirlo, 20-Simone Perrotta; 18-Antonio Cassano, 7-Alessandro Del Piero, 9-Christian Vieri (or 11-Bernardo Corradi)
Bulgaria (4-4-2): 1-Zdravko Zdravkov; 2-Vladimir Ivanov, 18-Predrag Pazhin, 5-Zlatomir Zagorcic, 22-Ilian Stoyanov; 13-Georgi Peev, 8-Milen Petkov, 15-Marian Hristov, 17-Martin Petrov; 21-Zoran Jankovic, 9-Dimitar Berbatov.
Referee: Valentin Ivanov (Russia)
Linesmen: Yury Dupanau (Belarus), Vladimir Eniutin (Russia)
Fourth official: Alain Hamer (Luxembourg)