Kalidou Koulibaly's towering header in added time has earned Napoli a 1-0 win over Juventus in Turin to leave the Serie A title race wide open.

The game was edging towards a goalless conclusion when the centre-back popped up late on to snatch victory for his side, closing the gap on Juve to just a point with four matches left to play.

Without back-to-back league wins in two months, Napoli knew that victory would be required to give them a realistic chance of making up the deficit on the leaders.

Lorenzo Insigne failed to make the desired contact inside the opening minute from a good position as the visitors made a bright start, but Miralem Pjanic was also close to a breakthrough with his free kick at the other end.

Saves were required to keep out Gonzalo Higuain and Mario Rui as the goalless first half transpired, while Marek Hamsik flashed one across the face of goal.

Juventus, who lost Giorgio Chiellini to injury early on, had the offside flag to thank 38 minutes in after Insigne thought that he had found a way through.

After a below-part first-half showing Juve made a second change at the break and reverted formation, but it would not have the desired effect.

Hamsik picked out the side-netting for the visitors and Insigne fired straight at Gianluigi Buffon, before the Italian keeper thwarted Piotr Zielinski.

The Azzurri almost saw things through for the point that would have kept them out in front heading into the final stretch, but Koulibaly met Jose Callejon's corner to win the match for Napoli at the death.

JUVENTUS (4-3-3): Buffon; Howedes, Benatia, Chiellini (Lichtsteiner 10'), Asamoah; Khedira, Pjanic, Matuidi; Douglas Costa (Mandzukic 71'), Higuain, Dybala (Cuadrado 46')

NAPOLI (4-3-3): Reina; Hysaj, Koulibaly, Albiol, Mario Rui; Hamsik (Zielinski 66'), Jorginho, Allan (Rog 80'); Callejon, Mertens (Milik 60'), Insigne