Inter down spirited Viola, Napoli lose more ground
Inter Milan scored three early goals before surviving a second-half fightback to beat 10-man Fiorentina 4-2 and give new coach Stefano Pioli his first win on Monday.
Mauro Icardi netted twice for Inter, taking his Serie A tally for the season to 12, while Fiorentina had defender Gonzalo Rodriguez sent off in first-half stoppage time.
Hosts Napoli lost ground on the leaders when they were held 1-1 by Sassuolo in the other match after Gregoire Defrel grabbed a memorable late equaliser for the visitors.
Napoli are seventh with 25 points, four behind second-placed AS Roma, while fifth from bottom Sassuolo became the first team to field an all-Italian starting line-up in Serie A this season.
Inter, who drew with AC Milan and lost to Israel's Hapoel Beer-Sheva in their first two games under Pioli, got off to a flying start at the San Siro.
Marcelo Brozovic fired them ahead after three minutes and Antonio Candreva tapped in a second from Ivan Perisic's cross six minutes later.
Icardi added a third after 19 minutes when he turned Rodriguez one way and the other, slipped past Davide Astori and sent a low shot under Ciprian Tatarusanu.
Nikola Kalinic pulled one back for Fiorentina in the 37th minute but the visitors were in more trouble when Rodriguez hauled down Icardi just outside the area and was shown a straight red card.
Fiorentina, though, found their game after the break and outplayed Inter with some slick passing.
They deservedly scored in the 62nd minute when Borja Valero sent Josip Ilicic bursting down the left and the Slovenian struck with an angled shot that was badly misjudged by Samir Handanovic.
Fiorentina continued to look threatening although Joao Mario missed a good chance for Inter on the break when he shot over with the goal at his mercy from six metres.
The visitors were always vulnerable to counter attacks and were caught out in stoppage time as Icardi sealed a win that lifted Inter to eighth place, one point ahead of their opponents.
Lorenzo Insigne gave Napoli a 42nd-minute lead when he collected Marek Hamsik's pass, cut inside and curled his shot into the net from the edge of the area.
But he was upstaged by substitute Defrel's 82nd-minute equaliser as the Frenchman met Marcello Gazzola's cross in his stride to volley the ball past Pepe Reina.