Inter Milan ended its five-match winless streak in all competitions by beating 10-man Bologna 3-1 on new manager Claudio Ranieri's debut, while injury-plagued AC Milan edged Cesena 1-0 with an early goal from Clarence Seedorf.
With seven points from the opening four rounds, Napoli and Fiorentina are level with Genoa, Juventus and Udinese.
Milan is two points behind and Inter is four points back.
On Sunday, it's: Chievo Verona vs. Genoa; Atalanta vs.
Novara; Cagliari vs. Udinese; Catania vs. Juventus; Lazio vs. Palermo; Siena vs. Lecce; and Parma vs. Roma.
In Bologna, Inter forward Diego Milito scored a penalty in the 81st minute and defender Lucio added another for the visitors in the 87th after Bologna's Alessandro Diamanti had leveled the match at 1-1 with a penalty in the 66th.
Giampaolo Pazzini had put Inter in front in the 39th and Bologna defender Archimede Morleo was sent off for taking Milito down from behind inside the area in the 80th, leading to Milito's penalty.
Both Diego Forlan and Esteban Cambiasso hit the woodwork for Inter.
Ranieri was hired on Thursday to replace Gian Piero Gasperini, who was fired a day earlier after Inter's 3-1 loss to newly promoted Novara.
"Let's hope this marks a turnaround," Milito said.
"Ranieri's arrival has given us a lot of enthusiasm, mostly at the psychological level. But I want to share these three points with Gasperini, too. They're also his, because he did a great job but unfortunately we weren't able to transmit that to the pitch." At the half-filled San Siro, Seedorf put the defending champions ahead with a sharply angled shot in the fifth minute that caught Cesena goalkeeper Nicola Ravaglia by surprise.
Milan was without injured forwards Zlatan Ibrahimovic and Alexandre Pato, as well as midfielders Massimo Ambrosini, Kevin-Prince Boateng and Gennaro Gattuso.
Milan's 19-year-old forward Stephen El Shaarawy had an excellent chance to double the lead in the 49th, but his close-range effort was blocked by Ravaglia.
At the San Paolo stadium, Napoli's "Three Tenors" _ Marek Hamsik, Ezequiel Lavezzi and Edinson Cavani _ threatened often early in the first half, and Fiorentina then took control with a series of counterattacks.
Riccardo Montolivo, Stevan Jovetic and Cesare Natali each had chances but Fiorentina missed the finishing touch of Alberto Gilardino, who is out for up to six weeks with a knee injury.
Napoli argued to no avail for a penalty after Fiorentina fullback Manuel Pasqual appeared to block a cross with his arm in the 61st.
Inter, Milan and Napoli are all in Champions League action this week.
Inter visits CSKA Moscow, having opened its European campaign with a shock 1-0 home loss to Turkish debutante Trabzonspor, Milan hosts Czech side Viktoria Plzen and Napoli makes its home debut against Villarreal.
Against Bologna, Ranieri handed Pazzini his first start of the league season, lining the Italy forward up alongside Forlan in a 4-3-1-2 formation.
Both forwards made impacts immediately, with Forlan hitting the post in the 13th and Pazzini then scoring with a long-range shot that Bologna goalkeeper Francois Gillet could only get a weak hand on.
Gillet also stopped an attempt from Inter defender Walter Samuel in the eighth minute at the Dall'Ara stadium.
Bologna captain Marco Di Vaio had the hosts' best chance of the half in the 11th after slipping behind Inter's defense, although with goalkeeper Julio Cesar well positioned his angled shot just missed the target.
In the 50th, Cambiasso hit the crossbar with a long shot, and Inter then struggled for a stretch.
Julio Cesar did well to push a header from Di Vaio wide in the 53rd, then made a diving save from a free kick by Gaston Ramirez in the 65th.
Samuel fouled Daniele Portanova to set up Diamanti's penalty, and then Inter took control again after Gillet exited with an apparent left shoulder problem in the 69th.
Lucio's goal came with a header following a free kick.
"It was good to start off on the right foot," said Ranieri, who has also managed Valencia, Chelsea, Juventus and Roma. "These guys needed to find a way to win and gain some self-confidence."