The southern Italian side currently trail Juve by four points in the Scudetto race, with five games remaining of the season.
Sunday sees the two hopefuls go head-to-head in Turin, and tensions were at boiling point prior to kick-off.
Napoli's team bus was barracked by supporters of the host team as it made its way to Juventus Stadium, but Sarri was in no mood to be intimidated.
Perched at the front of the vehicle, the coach responded by holding his middle finger up to his adversaries to brush off their insults.
Juve and Napoli have long been rivals, as two of the prime representatives of the tension between the north and south of Italy.
The rivalry came to a head in the 1980s, when Napoli idol Diego Maradona led the side to their best-ever spell while Juve were led by the great Michel Platini.
A further flashpoint came in 2016, when former Napoli favourite Gonzalo Higuain left for Turin - leading some fans to burn their jerseys in protest.