Napoli are the new leaders of Serie A after coming from behind to shock injury-hit Juventus.
Juve, missing some ten players to injury, went ahead through Amauri in the 61st minute.
But Napoli were quick to retaliate, Marek Hamsik drawing the hosts level just three minutes later.
Ezequiel Lavezzi then found the winner with ten minutes remaining to send Napoli a point clear at the top of Serie A and compound under-fire Juve boss Claudio Ranieri's concerns.
Joint Serie A top scorer Alberto Gilardino came off the bench and scored twice as Fiorentina beat ten-man Reggina 3-0.
Giampaolo Pazzini had put Fiorentina ahead with a drilled penalty five minutes before half-time after Reggina goalkeeper Andrea Campagnolo was given a red card for bringing down Mario Alberto Santana.
The in-form Gilardino had been rested ahead of Fiorentina's UEFA Champions League trip to Bayern Munich but came on to seal a third straight Serie A win for La Viola, steering a diagonal shot into the far corner in the 75th minute.
He then headed past substitute keeper Christian Puggioni, who rushed out from his goal, and ran on to slot the ball into an empty net nine minutes from time for his sixth league goal this season.