The 17-year-old midfielder could be available for a reduced transfer fee and could join fellow prospect Fabio Borini, who joined Chelsea, out the exit door.
Former Italian international Giancarlo Marocchi, now involved with Bologna's youth academy, admitted they will find it difficult to hang onto Mantovani.
"He is good, but we can't lock down all the promising youngsters. Unfortunately, with the rules here, we can't put all our promising kids on contracts to keep them away from foreign clubs. We have no weapons.
"But hopefully he will decide to stay with us."