Lazio on Sunday put daylight between themselves and their Champions League rivals as a Mobido Diakite goal two minutes from time gave them a 1-0 win over Cagliari.
The crucial strike cemented the Romans in third place, three points ahead of Napoli and Udinese in the race for the final Champions League qualification position.
It was a dramatic turnaround as Napoli had looked to be about to leapfrog Lazio when they led Catania 2-0 with the biancoceleste being held 0-0.
But Napoli conceded two quick goals from corners and Frenchman Diakite's late strike turned things on their head.
The centre-back headed home a Cristian Ledesma free-kick at the back post.
Napoli's home draw was a blot on an otherwise positive week in which they had reached the Italian Cup final with a 3-2 aggregate victory over Siena.
Blerim Dzemaili and Edinson Cavani looked to have given them victory before Nicolas Spolli and Davide Lanzafame pegged them back.
It took Napoli's unbeaten league run to nine games but they have drawn their last two.
The hosts struggled to break down their stubborn Sicilian opponents in the first half in Naples.
Walter Gargano and Marek Hamsik had both tried their luck from distance but goalkeeper Juan Pablo Carrizo was equal to those efforts.
They broke the deadlock just past the hour mark as the ball broke free 25 yards out and Dzemaili had time and space to crash an unstoppable shot into the top corner.
And just a few minutes later Napoli hit Catania on the counter-attack as Goran Pandev slipped in Cavani behind the defence.
He beat Carrizo with his first shot but it came back off the post, was missed by the back-tracking Spolli and came back to Cavani who this time fired home in off the same post he'd just hit.
The game seemed over but 15 minutes from time Spolli headed home a Cristian Llama corner to blow the game wide open.
And then five minutes from time Lanzafame reacted quickest after another Llama corner caused panic in Napoli's defence.
In other games Cesena stayed bottom after an entertaining 2-2 draw at home to Parma.
Adrian Mutu hit the bar for the hosts before Sebastian Giovinco teed up Sergio Floccari to give Parma the lead.
Goals from Mario Santana and Simone Del Nero put Cesena in charge but Gabriel Paletta snatched a point for the visitors, who remain one place and five points above the relegation zone.
Lecce failed to close that gap to Parma as they drew 0-0 at Novara, who remain second bottom and three points behind Lecce.
Rodrigo Palacio scored a minute from time to snatch a 2-2 draw for Genoa at home to Fiorentina.
On Saturday, Zlatan Ibrahimovic scored twice in AC Milan's 2-1 win over Roma as the champions moved seven points clear at the top.
Juventus have the chance to reduce that gap as they host Inter Milan in Sunday's late match.