Lorenzo Pellegrini is expected to be sidelined for 20 days after suffering a muscle injury to his right thigh.
The player wearing number seven was forced to leave the field shortly after the start of the second half against Slovan Bratislava.
Further details about Pellegrini’s condition are expected to be released in the coming hours.
His injury comes before the club’s upcoming Serie A fixtures against Napoli and Cagliari.