Morgan De Sanctis is likely to deputise in Milan.
Italy top Group B following Friday's 3-1 win in Armenia, when Buffon shone.
However, Mario Balotelli could return in time to face the Danes.
The Manchester city striker missed Friday's win in Armenia due to the flu.
"Team doctor Enrico Castellacci says he has responded well to tests," a statement said.
Balotelli missed Italy's opening World Cup qualifiers, against Bulgaria and Malta last month, after undergoing laser eye surgery.
Balotelli words: Natasha Todd
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