MILAN (AP) — Napoli's title chances diminished after it was held to a 0-0 draw at AC Milan on Sunday, in a result that suited neither team.
Napoli moved three points behind six-time defending champion Juventus, which hosts Sampdoria later.
It is also the capital derby later, with Lazio hosting Roma in a crucial match for both sides' Champions League chances.
The top four from Serie A qualify for Europe's premier club competition. Lazio and Roma are third and fourth, respectively, but on the same number of points as fifth-placed Inter Milan, which drew 0-0 at Atalanta on Saturday.
Milan, which had hopes of sneaking into the top four, is seven points behind.
Rossoneri goalkeeper Gianluigi Donnarumma made history as the youngest ever player to reach 100 Serie A appearances, aged just 19 years, one month and 21 days and he proved decisive in denying Napoli a last-gasp winner.
It was a strange match for Napoli goalkeeper Pepe Reina, who has agreed a free transfer to Milan at the end of the season.
Reina was immediately called into action against his future teammates, fingertipping an effort from Giacomo Bonaventura around the base of the post.
It was an aggressive start from Milan but Napoli began to take control after 15 minutes and Donnarumma did well to deny Dries Mertens after some good play from Jose Callejon and Lorenzo Insigne.
Insigne went close to breaking the deadlock 10 minutes before halftime, weaving his way through defenders before curling an effort inches wide of the right post.
Milan thought it had taken the lead four minutes later but Mateo Musacchio was offside when he fired in a rebound after Reina had parried Hakan Calhanoglu's powerful effort.
The match continued to be open after the break, with both sides seeking the win they needed for their respective ambitions.
Napoli came agonizingly close to snatching a stoppage-time winner as Arkadiusz Milik had time and space to control before shooting from six yards but Donnarumma pulled off a stunning save to fingertip the effort around his left post.
Fiorentina remained two points behind Milan and the final Europa League spot after a 0-0 draw at home to relegation-threatened Spal ended its six-match winning run.
Spal inched a point clear of the bottom three after its seventh match unbeaten.
Sassuolo moved four points above the relegation zone after drawing 2-2 against bottom side Benevento, which picked up its first point away from home.
Hellas Verona lost 2-0 at Bologna and is now three points from safety.