Napoli failed to take advantage of Inter and Juventus' Derby d'Italia draw as they were held to a goalless draw by Fiorentina at Stadio San Paolo.
It has been a disappointing nine days for Maurizio Sarri's side after losing to Juve in Serie A and being beaten 2-1 by Feyenoord as they exited the Champions League in midweek.
Sunday's 0-0 draw against Fiorentina is just as damaging as the Partenopei missed the chance to return to the summit, another blow to their Scudetto dreams.
For the opening 50 minutes they were very much second best to Fiorentina with visiting striker Giovanni Simeone wasting three clear-cut chances.
Eventually Napoli found some rhythm with Piotr Zielinski seeing a shot pushed onto the post, and captain Marek Hamsik rippling the side netting with a curling effort.
Dries Mertens' only sight of goal came in the final 20 minutes but he blasted straight at Marco Sportiello – much to the frustration of the home fans.
Napoli laid siege on the Fiorentina defence with time running out, but their search of a winning goal came up short, meaning they stay second, one point behind leaders Inter and one clear of Juve as a tight title race continues.
