Napoli coach Rafael Benitez has played down his side's title challenge after they moved two points clear of a host of Serie A rivals who failed to take maximum points at the weekend.
Benitez took over from Walter Mazzarri after Napoli's second-place finish behind Juventus last season and has steered the Partenopei to three wins in as many games to lead the Italian top flight ahead of Internazionale, Fiorentina and Juventus.
Juventus failed to take all three points in a 1-1 draw at Inter Milan on Saturday while AC Milan had to battle to secure a late and rather fortuitous draw away to Torino.
Fiorentina had hoped to capitalise by securing a win at home to visiting Cagliari that would have moved La Viola up to second, but had to settle for a 1-1 draw that was made worse by injuries and a late sending off.
Roma visit Parma on Monday, when a win for Rudi Garcia's visitors would hoist them up to at least second place.
Napoli, meanwhile, emerged with the biggest bragging rights after goals from Gonzalo Higuain and Jose Callejon secured victory over ten-man Atalanta at the San Paolo.
However former Liverpool and Chelsea boss Benitez says it's too soon to be dreaming of a first league title since the Diego Maradona era and the side that won titles in 1987 and 1990.
"The championship is decided at the end of the season, not after three games," Benitez said, whose side host Borussia Dortmund in their opening UEFA Champions League group game on Wednesday.
"We still have things to improve and we need to be ready for our next game."
While Napoli look forward to their European challenge, Fiorentina were counting early defeats which may come back to haunt them in their domestic and European bid for honours.
After Mauricio Pinilla scored in the 89th minute to level Valero Borja's 71st minute strike for the hosts, it emerged that Mario Gomez could be out for up to three months after spraining ligaments in his right knee following a clash with Cagliari goalkeeper Michael Agazzi.
If confirmed, Gomez would miss key Serie A games as well as Fiorentina's group campaign in the UEFA Europa League, which begins Thursday at home against Portuguese club Pacos Ferreira.
Fiorentina are also sweating on Colombian midfielder Cuadrado, who had to be replaced after suffering a dislocated shoulder in a clash with Radja Nainggolan.
And the hosts finished the game with ten men after David Pizzaro saw red in the dying minutes for dissent.
Fiorentina coach Vincenzo Montella was furious at what he said was unfair treatment of his side on the part of match officials.
"I can accept if we've done something wrong on the field of play, but how is it we are punished for this while you see players from other teams insulting referees so blatantly and are not punished?" Montella said.
Lazio, meanwhile, made amends for their 4-1 humbling by Juventus a fortnight ago with a 3-0 rout of Chievo, with first-half goals from Antonio Candreva, Luis Pedro Cavanda and Senad Lulic.
It moved Vladimir Petkovic's men up to seventh just behind promoted Livorno, who had Paulinho to thank for a brace in a 2-0 home win over Catania, a defeat which left the Sicilians second from bottom.
While Napoli sit top, Genoa were arguably in a more joyful mood after routing hosts Sampdoria 3-0 in a rain-hit Genoese derby.
Luca Antonini scored a superb volley after nine minutes and Emanuele Calaio doubled their lead shortly after the interval.
Francesco Lodi virtually sealed the points, and Genoa's first win of the season, with a superbly-struck free kick in the 66th minute to push Fabio Liverani's men up four places to 14th.