New life was breathed into the title race as Internazionale slipped to their first league defeat of the season, Marcelo Zalayeta's early goal giving Napoli a narrow 1-0 win at the Stadio San Paolo.

Inter now lead second-placed Roma by six points following the Giallorossi's comfortable 4-0 win over Parma a day earlier.

Elsewhere, substitute Pablo Osvaldo netted in injury time to give Fiorentina a thrilling 3-2 win over fellow Champions League hopefuls Juventus.

The result lifts the Viola to within a point of Juve in third place, but perhaps more importantly, the gap between them and fifth-placed Milan was extended to four points.

Napoli 1-0 Internazionale

In one of the games of the season so far, Napoli had a goalkeeping blunder to thank for the three points in an exciting and fast-paced affair in Naples.

Zalayeta's winner - which came as early as the third minute - stemmed from a terrible error of judgement from Inter keeper Julio Cesar who raced off his line to beat Ezequiel Lavezzi to the ball only for his control to let him down. The ball ran away from him and found Zalayeta, who clipped the ball over the keeper's head, under the bar and into the back of the net.

Roared on by the partisan crowd, Napoli were nothing short of sensational during the first half and threatened to swamp the champions such was the ease with which they created goalscoring opportunities.

Decent chances fell to the effervescent Lavezzi, Matteo Contini, Marek Hamsik, Paolo Cannavaro and Zalayeta during the opening period, but the nearest the hosts came to doubling their lead came from an unlikely source, just before the half time whistle.

It was Inter defender Marco Materazzi whose comically sliced clearance brought the best out of Julio Cesar who was forced to scramble back and paw the ball off the goal line to spare his team-mate's blushes.

Inter rarely showed themselves as an attacking force in the first half, David Suazo going closest when he brought Matteo Gianello into action with a low drive in the 19th minute.

After the fireworks of the first half, it was no surprise that the tempo of the second was a little more subdued, as Inter slowly worked their way back into the game.

But as the champions committed more players forward in search of an equaliser, they left gaps at the back and Napoli maintained their threat on the counter.

One such break gave the hosts the perfect opportunity to seal all three points in the 75th minute, after Julio Cesar was adjudged to have tripped the breaking Walter Gargano in the box.

The keeper was lucky to stay on the pitch - he only saw yellow - but Zalayeta was unable to seal the win from the resulting penalty as Julio Cesar made immediate amends by tipping the Uruguayan's kick round the post.

But Inter could not repeat their heroics of midweek - when Javier Zanetti's late strike salvaged a point against Roma - and Napoli were not made to regret that missed spot kick.

The three points moved the Azzuri to within a point of tenth placed Atalanta.

Juventus 2-3 Fiorentina

In Turin, Argentina-born striker Osvaldo's late header finally settled a match that had swung both ways during the 90 minutes.

Fiorentina started the stronger of the two sides and deservedly took the lead in the 19th minute when Massimo Gobbi finished coolly after playing a neat one-two with Martin Jorgensen that had carved open the Juve defence.

The goal rocked the hosts and the Viola could easily have capitalised even further minutes later, but Gigi Buffon managed to push Zdravko Kuzmanovic's effort onto the upright and keep the score at 1-0.

It proved to be a turning point, as Buffon's save instilled some confidence into Juve who grew in stature as game wore on.

And that showed when Momo Sissoko opened his Bianconeri account to draw Juve back on level terms in the 29th minute, the former Liverpool midfielder improvising brilliantly to fire an overhead kick past Sebastien Frey in the Fiorentina goal.

After the break, Juventus continued their resurgence and it came as no surprise when they took the lead through Camoranesi's well taken back post volley just before the hour mark.

But Fiorentina were not finished there and restored parity thanks to another substitute, Papa Waigo, with 15 minutes remaining. The Senegalese striker fired a crisp drive into the far corner to register his second goal in as many games, having already downed Livorno midweek.

The headlines were saved for Osvaldo though, as he headed Papa Waigo's cross past Buffon deep in time added on to hand the Viola all three points.

The only cloud on an otherwise triumphant day for Cesare Prandelli's side was Osvaldo's sending off - for a second yellow card after taking off his shirt in a flurry of excessive, and ill-advised, celebration.

Cagliari 2-1 Genoa

Defender Alessandro Lucarelli headed Genoa in front in the 15th minute but Robert Acquafresca struck back for Cagliari with a splendid volley in the 29th.

Acquafresca then looped in a header that bounced into the net via the post and goalkeeper Rubinho's shoulder for a win that boosts the basement side's slender hopes of avoiding the drop.

The Sardinians are in big trouble after being deducted three points on Friday for breaking federation rules by taking a legal dispute with a former player to the civil courts without permission.

Empoli 0-2 Siena

Defender Daniele Portauova's 33rd-minute header and Christian Rigano's stoppage-time goal gave Siena victory over their Tuscan rivals, who had Davide Moro sent off late on for a second yellow card.

Livorno 1-0 Catania

Alessandro Diamanti's powerful shot from outside the box in the 62nd minute ended a run of three straight defeats for Livorno, lifting them out the relegation zone above Catania.

Reggina 0-0 Palermo

Palermo's Edinson Cavani came closest to scoring in this goalless draw with a shot that flew just over the bar after a counter-attack in the 55th.

The Sicilians had a Cristian Zaccardo goal disallowed for offside in the first half.

Sampdoria 2-2 Torino

Luigi Sala equalised for the home side just before half-time with a diagonal strike after Gianluca Comotto's 18th-minute shot from outside the area slipped through goalkeeper Luca Castellazzi's fingers on the way to the net.

Torino's David Di Michele earned and converted a penalty in the 51st but Antonio Cassano levelled again for Samp just a minute later.

Cassano protested wildly after being sent off for a second yellow card in the closing stages and continued to shout abuse at the referee for a spell from the sidelines.

Udinese 2-0 Atalanta

Italy strikers Fabio Quagliarella and Antonio Di Natale decided the game with two first-half goals in quick succession.

Mike Hytner / Eurosport / Reuters