Inter Milan suffered a humiliating first defeat of the season as it was routed 4-1 by last-placed Cagliari in Serie A on Sunday, while AC Milan was held to a 1-1 draw at Cesena.
Cagliari had lost its last three matches but gained an advantage when Inter captain Yuto Nagatomo was sent off in the 27th minute following two yellow cards.
Albin Ekdal, who had scored three goals in 77 appearances for Cagliari, doubled his tally for the club with a 15-minute hat trick.
It would have been worse for Inter if Samir Handanovic had not saved a penalty.
Napoli won 1-0 at Sassuolo in the lunchtime kickoff.
Fiorentina also drew 1-1 at Torino as did Chievo Verona at home to Empoli.
Juventus and Roma both maintained their perfect start to the season with victories on Saturday.
Genoa hosts Sampdoria in a derby match later.
Cagliari took the lead in the 10th minute when Nagatomo failed to deal with a long ball and headed straight at Marco Sau, who fired home.
But Inter was back on level terms eight minutes later when Rodrigo Palacio took a free kick quickly and set up Pablo Osvaldo.
The turning point came shortly afterward when Nagatomo picked up two yellow cards in as many minutes and was dismissed.
Cagliari immediately restored its advantage as Handanovic did well to parry a fierce strike from Daniele Dessena, but Ekdal pounced on the rebound.
Ekdal doubled his tally five minutes later, tapping in Victor Ibarbo's cross after a great run from the Colombia winger who had bamboozled the Inter defense.
It almost got worse shortly before halftime when Nemanja Vidic mistimed a sliding tackle on Sau in the area. However, spot-kick specialist Handanovic saved Andrea Cossu's penalty.
But Cagliari did get a fourth moments later when Ekdal completed his hat trick after Inter failed to clear a corner.
Osvaldo thought he had pulled one back for Inter shortly after the interval but his effort was ruled out for offside.
City rival Milan was also forced to play at a numerical disadvantage after Cristian Zapata was sent off in the 73rd minute for denying Gregoire Defrel a clear scoring opportunity.
Cesena had taken a shock lead in the 10th minute when Christian Abbiati - replacing the injured Diego Lopez - fumbled a simple attempt from Guido Marilungo and Davide Succi was on hand to tap in the rebound.
Jeremy Menez almost recorded his fourth goal of the season but it was struck off after Fernando Torres was adjudged to be offside.
Milan did level in the 19th when Adil Rami headed in Keisuke Honda's corner.
Stefano Lucchini thought he had snatched all three points for Cesena at the death, but the referee had already stopped play for Emmanuel Cascione's push on Mattia De Sciglio.
