Fiorentina coach Vincenzo Montella rates Napoli as title contenders.
Fiorentina fought back to win their opening Serie A game 2-1 against Udinese, but travel to Napoli.
"It is going to be a delicate encounter, as we are facing a team of the highest level. I strongly believe Walter Mazzarri's side are Scudetto contenders.
"We have a few options in defence and I don't want to give anything away. We could play with three at the back or four. We'll see."