The on-loan Roma forward pulled up during Sunday's 4-2 defeat to his parent club, with medical staff confirming the extent of the damage today.
A statement on genoacfc.it read: "Examinations conducted at the
"The striker has undergone both an MRI scan and an ultrasound.
"The medical staff estimate that he will be able to return to athletic activities in 45 days."
Borriello has scored three goals in seven appearances since returning to the Stadio Luigi Ferraris in August.
Napoli president Aurelio De Laurentiis insists there is 'nothing official yet' regarding its hunt for a coach amid widespread speculation Rafael Benitez will be the new man in the hotseat.