Ciro Immobile's second-half brace for Lazio condemned Serie A champions Juventus to a first home defeat in over two years, a 2-1 loss on Saturday that allowed Napoli to pull clear by beating Roma 1-0.

Paulo Dybala missed a late penalty as the Turin giants lost at home for the first time since August 2015 -- ending a run of 38 wins and three draws for the six-time consecutive Serie A winners.

Lorenzo Insigne scored early at Rome's Olympic stadium as Napoli maintained their perfect start with an eighth win in as many games.

Napoli go five points of the champions who are now in third position, equal on 19 points with Lazio and Inter Milan, who go head to head with city rivals AC Milan on Sunday night.

For Juventus coach Massimiliano Allegri the warning signs had been there early in the season and during a 2-2 draw against Atalanta in their last game.

"We had the warning signs against Torino, Sassuolo and Atalanta. We have these drops in concentration and pay a heavy price for them," lamented Allegri.

"Between Bergamo (Atalanta) and today we have dropped five points and haven't realised yet that to win the Scudetto you must fight every single day.

"Now we've got an important game on Wednesday against Sporting in the Champions League and we have to win."

Napoli, meanwhile, were pushed hard by Roma in the second half after Insigne struck on 20 minutes with the only goal of the game, making the most of the misfortune of Roma skipper Daniele De Rossi to fire in past Alisson for the 100th club goal of his career.

Two Edin Dzeko headers -- the first cleared by Pepe Reina after 70 minutes and the second which flew over the bar six minutes from time -- kept Roma hopes alive.

But a second defeat at home against a big team after Inter Milan gives Eusebio Di Francesco a lot to think about before next week's Champions League trip to Chelsea.

"I fear we had a bit too much respect for Napoli in the first half," said Di Francesco.

Maurizio Sarri's Napoli, meanwhile, head to Manchester City full of confidence.

- Immobile impresses -

Juventus got off to a bright start in Turin with Brazilian Douglas Costa, on loan from Bayern Munich since July, scoring his first goal after 23 minutes off a rebound following a Thomas Strakosha save from Sami Khedira.

But it was all one-way traffic for Lazio in the second half as Immobile pulled the Romans ahead with a seven-minute double, the second a penalty past Gianluigi Buffon on 54 minutes to move top of the Serie A scorers ahead of Dybala with 11 goals in eight matches.

"We're going to enjoy this important win. It's a success that will give us a boost for what's to come," said Immobile.

Dybala came off the bench and his effort hit the bar, but there was more drama in stoppage time when the Argentine striker stepped up for the last kick of the game only to see his penalty saved by Strakosha.

Lazio had not beaten Juventus in Serie A in Turin since 2002 but had won their last meeting this year in the Italian Super Cup, which the Roman club won 3-2 in a stoppage-time victory.

"This is a result that will go down in the history of this club," said coach Simone Inzaghi.

"We achieved something remarkable this evening."

"It's never easy with the fans and atmosphere in Turin, as there's a reason they haven't lost here in almost three years.

"I felt that we could hurt Juve if we just hung in there. Some people said we’d be in ninth or 10th place this season, which is unfair, so now it’s only right that people talk about us."

Source: AFP