A spectacular Gregoire Defrel volley gave Sassuolo the 1-1 draw, as Napoli are left with more regrets despite a Lorenzo Insigne stunner.
Both sides had struggled with injury problems and had disappointing midweek European results. The Partenopei gave Manolo Gabbiadini his first Serie A start since the red card at Crotone, while Ivan Strinic had only his third appearance of the season to rest defenders. The Neroverdi missed Domenico Berardi, Alfred Duncan, Tim Letschert, Davide Biondini and not fully fit Lorenzo Pellegrini.
Sassuolo became the first Serie A side this season to field an all-Italian starting XI.
The opening stages saw several yellow cards and the first chance for Sassuolo, as Antonino Ragusa’s volley was charged down in the area from a Marcello Gazzola cross. Jose Callejon responded with a fierce strike that Andrea Consigli smothered.
The hosts started to step up the pace with Lorenzo Insigne’s right-foot curler inches past the far top corner, then Kalidou Koulibaly’s cross-shot was deflected on to the side-netting.
An Insigne cross to the back stick for Callejon drifted inches wide, as nobody got the touch when Federico Peluso and Consigli left it for each other.
Sassuolo’s rotten luck got even worse, as Matteo Politano finally succumbed to an ankle injury caused by Strinic in the opening minutes and had to limp off.
Luca Mazzitelli brought down Marek Hamsik right on the edge of the box as the Slovak had turned on the turbo to burst through the centre.
Napoli did make their domination finally count when Insigne took down a long Hamsik ball with great first touch, cut inside and curled a right-foot stunner from distance that looped over Consigli to dip under the crossbar, albeit with a slight deflection off Paolo Cannavaro.
After the restart Insigne sparked a rapid counter that Callejon laid off for Gabbiadini, but the powerful strike was too central and punched away by Consigli.
Yet Sassuolo almost grabbed an equaliser when Gazzola’s assist found Simone Missiroli for a free header on to the crossbar.
Dries Mertens came off the bench and almost immediately got a yellow card, meaning he’ll be suspended for the big showdown with Inter.
Callejon over-hit the cross for Insigne, who sliding in at the back post couldn’t keep it on target, and Mertens forced a tough save out of Consigli from distance.
As Napoli stepped on the gas, Sassuolo introduced hitman Gregoire Defrel to set up a fiery final 20 minutes. Hamsik’s cross-shot was beaten away at the near post and Cannavaro crucially sprinted across with a sliding tackle to block Insigne’s effort.
Defrel made all the difference, because Gazzola had been putting crosses in all night from the right hand side, but this time the Frenchman was on the end of it for an absolutely sensational volley from 14 yards, giving Pepe Reina no chance.
Consigli acrobatically flapped an Emanuele Giaccherini cross-shot away from both the crossbar and Callejon’s head.
With almost the last kick of the game, Callejon’s angled drive beat Consigli only to bounce off the inside of the far post.