Former AC Milan star Fulvio Collovati says the club should get behind Suso and Giacomo Bonaventura.
The World Cup winner rates the midfield pair as crucial this season.
He said: "I don't see fitness issues, so firing the fitness coach looked a bit like seeking a scapegoat, in my view. Milan already had quality players, so they tried to change too much.
“If you are now forced to leave out Suso and Bonaventura to make way for the new players, that is a mistake. Milan won the Italian Super Cup last season thanks to Suso and Bonaventura's equaliser.
“If those two play against Inter, then yes, Milan can do damage in the derby. Whether or not Montella continues in the job will depend on how he emerges from the derby."