Milan know they must win in Siena to stave off Fiorentina and secure a Champions League spot, but they bench Stephan El Shaarawy.
The Stadio Artemio Franchi hosts this 19.45 UK time (18.45 GMT) kick-off, click here for a match preview .
Only a victory will ensure third place, as a draw and Fiorentina win in Pescara would send the Viola through thanks to a superior head-to-head record.
Massimiliano Allegri could be making his final appearance on the Milan bench amid reports of a deal with Roma.
Sulley Muntari is suspended after his red card for manhandling the referee, while Kevin-Prince Boateng, Bojan Krkic and Nigel De Jong are injured.
Riccardo Montolivo is available again after his thigh strain, but El Shaarawy is surprisingly benched in favour of Robinho and M’Baye Niang.
Mathieu Flamini is also dropped despite his recent scoring streak.
Siena are already relegated and on a run of five consecutive defeats, but put up a real fight to trouble Napoli last week.
Nicola Pozzi and Simone Vergassola are out of action.
Siena: Pegolo; Terzi, Terlizzi, Felipe; Vitiello, Calello, Bolzoni, Della Rocca; Rubin, Rosina; Emeghara
Milan: Abbiati; Abate, Zapata, Mexes, De Sciglio; Montolivo, Ambrosini, Nocerino; Niang, Balotelli, Robinho