The Naples side seemed on course for only their second win in six games in all competitions after returning striker Edinson Cavani put them in the lead in the 6th minute.
However, an injury-time blunder from Salvatore Aronica, who had only been on the field five minutes after coming on as coach Walter Mazzarri sought to shore up defensively and cling on to their one-goal advantage, gifted the ball to Gianluca Sansone who then displayed commendable calm to round home keeper Morgan De Sanctis and slot into an empty net and ensured his side would claim a share of the spoils.
Meanwhile on Saturday, Inter Milan came back from a goal in the first minute to bring an end to Juventus' 49-game unbeaten run in Serie A with a 3-1 win at the Juventus Stadium.
Arturo Vidal's goal after 19 seconds served only to inspire Inter, who turned the game around in the second half to move to within a point of Juve at the top of the table.
Diego Milito was on target twice for Andrea Stramaccioni's side, including an equaliser from the penalty spot, before Rodrigo Palacio sealed Inter's seventh win in a row in the last minute.
It was also a good night for Inter's city rivals AC Milan, who romped to a 5-1 win over Chievo at the San Siro.
Urby Emanuelson opened the scoring in the 16th minute, although the lead lasted only two minutes before Sergio Pellissier levelled.
Riccardo Montolivo and Bojan Krkic gave Milan a comfortable half-time lead before their top goalscorer Stephan El Shaarawy got his customary goal in the 75th minute.
Giampaolo Pazzini added a fifth to wrap up victory with the last kick of the game.
Saturday's Serie A Results
Sunday's Serie A Results