Napoli give Axel Tuanzebe his full debut in defence behind Dries Mertens and Andrea Petagna, while Fiorentina seek an upset with Dusan Vlahovic and Nico Gonzalez.
It kicks off at 17.00 GMT, you can follow all the build-up and action as it happens from this game and Milan-Genoa on the LIVEBLOG.
This is the Coppa Italia Round of 16, so the winner will be decided on the day after 90 minutes, extra time or penalties.
The winner of this tie between Napoli and Fiorentina will go on to face Atalanta in the quarter-final next month.
Napoli throw Tuanzebe straight into the starting XI for his full debut after a late substitute appearance in the 1-0 win over Sampdoria, which was just hours following his loan move from Manchester United.
Lorenzo Insigne is injured, Piotr Zielinski and Mario Rui have COVID-19, Kalidou Koulibaly, Andre Frank Zambo Anguissa and Adam Ounas are on Africa Cup of Nations duty, while Victor Osimhen only just returned to training.
Fiorentina are coming off a shock 4-0 defeat to Torino and really want to make up for that humiliation.
Lucas Martinez-Quarta is injured and Sofian Amrabat is on international duty.
The good news is that Bartlomiej Dragowski makes his comeback after several months out with a serious thigh injury.
Napoli: Ospina; Di Lorenzo, Rrahmani, Tuanzebe, Ghoulam; Demme, Lobotka; Politano, Mertens, Elmas; Petagna
Fiorentina: Dragowski; Venuti, Milenkovic, Nastasic, Biraghi; Castrovilli, Torreira, Duncan; Gonzalez, Vlahovic, Saponara