According to Gazzetta dello Sport, The following is the probable formations for Benevento - Milan.
Théo Hernandez will not be playing the match due to receiving a yellow card against Lazio, so he will be replaced by Diogo Dalot.
AC Milan: 4-2-3-1: Donnarumma; Calabria, Kjaer, Romagnoli, Dalot; Tonali, Kessié; Diaz, Calhanoglu, Rebic; Leao.
Benevento : 4-3-2-1: Montipo; Barba, Glik, Tuia, Letizia; Improta, Schiattarella, Hetemaj; Caprari, Ionita; Lapadula.
I think its better if we start the first half with Kalulu. Kjaer may be not ready to play full 90mn.