Mario Lemina had put the Bianconeri ahead after 21 minutes, but Daniele De Rossi bundled in from point-blank range moments later.
The gap at the top of the table has now been sliced to just four points with two rounds to go, while Napoli are five points adrift of the Serie A leaders.
Roma fought back from a goal down to defeat Juventus 3-1, throw a spanner in the Scudetto works and recapture second place from Napoli.
This is not the best build-up for Juventus, who are back at the Olimpico on Wednesday night against Lazio in the Coppa Italia Final.
Or see how all today’s Serie A games unfolded
It’s a shock for Max Allegri’s men, who have now picked up just two points from the las在线外围投注t thre21点官网e rounds.
In the second half, Stephan El Shaarawy’s deflected snooker-shot snuck in at the far post and Radja Nainggo皇冠外围投注lan smashed a third in at Gigi Buffon’s near post.