Milan have Theo Hernandez and Hakan Calhanoglu back, but lose Simon Kjaer and Davide Calabria, while Napoli rely on Dries Mertens and Lorenzo Insigne.
It kicks off at San Siro at 19.45 GMT.
You can follow all the build-up and action as it happens on the LIVEBLOG.
Stefano Pioli has numerous injury problems, yet keeps churning out impressive results in both Serie A and the Europa League.
Milan have Theo Hernandez and Hakan Calhanoglu back, but lose Simon Kjaer and Davide Calabria, while Napoli rely on Dries Mertens and Lorenzo Insigne.
It kicks off at San Siro at 19.45 GMT.
You can follow all the build-up and action as it happens on the LIVEBLOG.
Stefano Pioli has numerous injury problems, yet keeps churning out impressive results in both Serie A and the Europa League.
Kjaer scored a stoppage-time header in Thursday’s 1-1 Europa League draw with Manchester United.
However, he is not fully fit, with Davide Calabria, Alessio Romagnoli, Zlatan Ibrahimovic, Mario Mandzukic, Ismael Bennacer and Daniel Maldini already out injured.
It means Fikayo Tomori and Matteo Gabbia form an all-new partnership in central defence, with the Italian not featuring since December 13 due to a knee ligament issue.
The good news is that Theo Hernandez and Hakan Calhanoglu are back in the starting XI, with Ante Rebic available on the bench.
Napoli have problems too, as Hirving Lozano, Andrea Petagna, Kostas Manolas, Amir Rrahmani and Faouzi Ghoulam did not make the trip.
This is the first time Gennaro Gattuso has come to San Siro as an opponent against his beloved Milan, where he spent over 13 years as a player and a coach.
Mertens is preferred to Victor Osimhen, with neither of them really fit for 90 minutes, supported by Matteo Politano, Lorenzo Insigne and Piotr Zielinski.
Milan: G Donnarumma; Dalot, Gabbia, Tomori, Theo Hernandez; Kessie, Tonali; Castillejo, Calhanoglu, Krunic; Leao
Milan bench: A Donnarumma, Tatarusanu, Kalulu, Kjaer, Brahim Diaz, Hauge, Meite, Saelemaekers, Rebic
Napoli: Ospina; Di Lorenzo, Maksimovic, Koulibaly, Hysaj; Fabian Ruiz, Demme, Zielinski; Politano, Mertens, L Insigne
Napoli bench: Meret, Contini, Mario Rui, Zedadka, Costanzo, Elmas, Lobotka, Bakayoko, Osimhen, Cioffi
Ref: Pasqua