Napoli conceded top spot in Serie A to red-hot Atalanta on Sunday after falling to a 1-0 home defeat to Lazio and dropping to two points from the summit.

Fiorentina earlier remained on Napoli's heels after their 1-0 home win over Cagliari in their first league match since midfielder Edoardo Bove's sudden collapse last weekend.

In soaking wet Naples, Gustav Isaksen stunned the home fans with a brilliant strike, which rifled past Napoli goalkeeper Alex Meret and kept Lazio right in a crowded league title race.

Marco Baroni's Lazio are fifth but only three points behind new leaders Atalanta, who sit top of the pile thanks to a club record-equalling ninth straight league win over AC Milan on Friday.

"The boys showed how fired up they were and their work ethic," Baroni told DAZN.

"We're facing teams built to win, and the only way we can get there (to their level) is with good football. That's the only way we can play."

Napoli now have three teams just a point behind them, including Inter Milan and Lazio who also dumped Antonio Conte's team out of the Italian Cup on Thursday.

Khvicha Kvaratskhelia and Andre-Frank Zambo Anguissa both struck the woodwork for Napoli, who are hunting a fourth league title after being crowned champions in 2023.

But the hosts were frustrated by dogged Lazio, who were largely on the back foot but came close on a couple of occasions before Isaksen smashed in his second Serie A goal of the season.

Isaksen had stung Meret's fingers with a similar effort midway through the first half, while Fisayo Dele-Bashiru crashed a rocket of a shot onto the bar six minutes after the break.

Kvaratskhelia skimmed the crossbar with a free-kick in first-half stoppage time, while Anguissa glanced a header onto the post moments before Isaksen struck his winner.

"I think tonight showed that the direction we're heading in is the right one," insisted Conte to DAZN.

"We need to improve, especially when it comes to creating chances because too often the final pass is missing and tonight was not the first time."

- Fiorentina in the hunt -

Fiorentina are, alongside third-placed Inter, level on 31 points with Lazio after they edged past Cagliari earlier on Sunday.

Danilo Cataldi fired in the only goal of the game in the 24th minute to give Fiorentina an eighth straight win in Italy's top flight, not counting their interrupted match with Inter Milan which was goalless when Bove collapsed.

Promising midfielder Bove, 22, has been in Florence's Careggi hospital for a week as he undergoes tests, with reports in Italian media saying that his career in Italy is effectively over.

Before kick-off, Fiorentina captain Luca Ranieri expressed anger at reports that Bove was set to have a defibrillator fitted, which would force him to look for a club abroad due to stringent health regulations in Italian sport.

"I ask for a bit of respect for both him and for his privacy because a series of untrue things have been written and said about him," said Ranieri.

Raffaele Palladino also insisted that he and his players were "waiting to welcome him back on the pitch soon".

Cataldi dedicated his superb opener to his good friend and fellow Roman Bove, with the pair on loan at Fiorentina from capital city clubs Lazio and Roma.

The 30-year-old ran to a pitchside camera to make the number four -- Bove's shirt number -- and a heart with his fingers after rifling Lucas Beltran's lay-off into the top corner.

Cataldi's goal left spirited Cagliari 15th, two points above Verona who dropped into the relegation zone on goal difference after being flattened 4-1 by Empoli.

Verona dropped behind Como following a heavy home defeat -- their seventh loss in eight league matches -- and an entertaining 2-2 draw for Cesc Fabregas' side at bottom club Venezia.