Pirlo and Antonini will miss the match against Sampdoria on Saturday.
The two players, who also missed out on the 2-0 win over Auxerre on Tuesday, were not included in Allegri's 20-man squad as they continue to harbour minor knocks.
The Rossoneri have found success without Pirlo in the line-up, using a midfield quartet of Mathieu Flamini, Gennaro Gattuso, and Massimo Ambrosini supporting the more attacking Clarence Seedorf.
Alexandre Pato, Filippo Inzaghi, and Massimo Oddo will also miss the contest. Milan are currently first in the Serie A standings with 29 points, three ahead of second-placed Lazio.
Full Milan Squad:
Goalkeepers: Abbiati, Amelia, Roma
Defenders: Bonera, Jankulovski, Nesta, Papastathopoulos, Thiago Silva, Zambrotta, Yepes
Midfielders: Abate, Ambrosini, Boateng, Flamini, Gattuso, Seedorf, Strasser
Strikers: Ibrahimovic, Robinho, Ronaldinho.
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