Napoli have suffered a catastrophic setback in their quest for the Serie A title as they fell to a 3-0 defeat at Fiorentina on Sunday.

Giovanni Simeone was the hero for the Viola and for the Bianconeri, scoring a hat-trick to keep the Partenopei four points adrift of leaders Juventus with just three games to go.

Ahead of kickoff, the onus was on second-placed Napoli to triumph at the Stadio Artemio Franchi after the Old Lady beat Inter Milan 3-2 on Saturday to open up a four-point gap at the top.

Napoli were hamstrung from the opening stages of the encounter as Kalidou Koulibaly was sent off on eight minutes for denying Simeone a clear goalscoring opportunity just outside the box.

The deadlock was broken shortly after the half-hour mark when Simeone ran towards a Cristiano Biraghi ball over the top, claimed possession and slotted through the legs of the onrushing Pepe Reina.

Simeone then grabbed his and Fiorentina's second on 62 minutes as a corner kick which caused havoc in the Napoli defence culminated in the 22-year-old striking home on the rebound.

The Atletico Madrid manager's son went on to claim the match ball with an injury-time third, running on to a through-ball, shrugging off Mario Rui and placing the angled drive past Reina.

FIORENTINA (4-3-3): Sportiello; Laurini (Gaspar 62'), Milenkovic, Pezzella, Biraghi; Veretout, Badelj (Cristoforo 83'), Benassi; Saponara (Eysseric 74'), Chiesa; Simeone

NAPOLI (4-3-3): Reina; Hysaj, Albiol, Koulibaly, Rui; Allan, Jorginho (Tonelli 10'), Hamsik (Zielinski 57'); Callejon, Mertens (Milik 57'), Insigne