Genoa handed Serie A leaders and titleholders Juventus a dramatic first league defeat of the season when Luca Antonini scored in the fourth minute of stoppage time to give them a 1-0 win.
Genoa goal-keeper Mattia Perin kept Juventus at bay, his repertoire of saves including two brilliant stops from Alvaro Morata, and Angelo Ogbonna hit the crossbar for the visitors, before Antonini scored with almost the last kick of the game.
Napoli continued on their erratic way as they threw away chances in a 1-1 draw at Atalanta where Jose Callejon fired over an open goal and Gonzalo Higuain scored a late equaliser, only to miss a stoppage time penalty.
Inter Milan, for the second successive match, won 1-0 with a controversial penalty, this time against previously unbeaten Sampdoria, as Mauro Icardi converted in the 89th minute amid angry protests from the visitors.
Mattia Destro and Daniele De Rossi gave AS Roma a 2-0 win over promoted Cesena as they pulled level with Juventus at the top. Both have 22 points from nine games, six ahead of AC Milan, Sampdoria and Udinese.
Cagliari and AC Milan drew 1-1, Victor Ibarbo opening the scoring before Milan's Giacomo Bonaventura replied with a superb curling effort, and Palermo beat Chievo 1-0.
Matteo Darmian's early goal gave Torino a 1-0 win over Roberto Donadoni's Parma, who are bottom after losing eight of their nine games.