Turin - Senegalese defender Kalidou Koulibaly's last-gasp goal kept Napoli's title hopes alive with a 1-0 win against Juventus to close the gap to just one point on the Serie A champions.
Koulibaly headed the winner off a corner in the final minute to give Napoli their first ever victory at the Allianz Stadium.
Six-time defending champions Juventus's lead at the top of the table has been cut to just one point with four games left.
Juventus have 85 points from 34 games with Napoli, bidding for a third Scudetto after 1987 and 1990, on 84.
But the champions have a difficult run-in to the season against Inter Milan and Roma - both fighting for Champions League places.
Juventus lost defender Giorgio Chiellini to injury in the first half while Miralem Pjanic hit the post.
Napoli also went close early through Marek Hamsik before Lorenzo Insigne had a goal disallowed for offside.