Sampdoria keeper Emiliano Viviano came to to rescue as Sassuolo threatened to condemn them to a first defeat.
AC Milan edged a nine-goal thriller with Parma at the Stadio Tardini to join Juventus and Roma at the top of Serie A.
Sampdoria picked up their first win of the new season with a 2-0 victory over Torino at the Stadio Luigi Ferraris.
Sampdoria goalkeeper Sergio Romero has denied suggestions that he rejected a move to Manchester United on transfer deadline day.
Palermo were denied a victory on their return to Serie A after a stoppage-time equaliser for Sampdoria.
AC Milan beat Lazio 3-1 in Filippo Inzaghi's first Serie A game in charge, while Inter Milan's Nemanja Vidic saw red.
Live only on