FLORENCE, Italy, Oct 3 (Reuters) - Napoli came from behind to earn a 2-1 victory at Fiorentina in Serie A on Sunday, ensuring they remain the only side in Europe"s top five leagues with a 100% record this season. The league leaders started sluggishly and were punished in the 28th minute as Lucas Martinez Quarta took advantage of some slack marking to fire Fiorentina into a deserved lead. The opener acted as a wake-up call for Napoli with Hirving Lozano firing them level 10 minutes later, following up after goalkeeper Bartlomiej Dragowski had brilliantly saved Lorenzo Insigne"s penalty. Victor Osimhen then almost edged Napoli in front before halftime with a spectacular overhead kick. However, the visitors did not have to wait much longer to complete the turnaround, with Amir Rrahmani giving them a 2-1 lead in the 50th minute. Napoli had chances to extend their advantage but saw the game out to secure a seventh straight win and stay top, two points clear of second-placed AC Milan, who beat Atalanta 3-2. read more Fiorentina remain fifth after their third defeat of the season. It is only the second time in Napoli"s history that they have won their opening seven matches of a Serie A campaign, but that was still not enough to please coach Luciano Spalletti. "We still need to improve, to see out results after battling to be in front," he told DAZN. "This (margin of) victory is small and there was a chance to do better. Some players are still not fully fit. Playing every three days is not easy. We still have a lot to do."