Mauricio Pinilla climbed off the bench to net a late winner for Genoa at the expense of 10-man Lazio.
AC Milan edged a nine-goal thriller with Parma at the Stadio Tardini to join Juventus and Roma at the top of Serie A.
Fiorentina could not find a way past visiting goalkeeper Mattia Perin as they were held to a goalless draw by 10-man Genoa.
AC Milan beat Lazio 3-1 in Filippo Inzaghi's first Serie A game in charge, while Inter Milan's Nemanja Vidic saw red.
Jonathan De Guzman earned Napoli a winning start to the Serie A season as they beat Genoa 2-1.
Iago Falque has departed Tottenham for Serie A side Genoa for a fee reported to be around £4m – pending a medical.