Lorenzo Insigne's 86th minute equaliser earned Napoli a hard-fought point against mid-table side Sassuolo in what was a toothless display at the Mapei Stadium.
The visitors, who made eight changes after their 3-0 win against Red Bull Salzburg in the Europa League on Thursday, faced a difficult first half with the Neroverdi creating plenty of opportunities. Former Chelsea winger Jeremie Boga caused the Napoli back line problems in the opening minutes, with his curling effort going just wide after a brilliant run.
Carlo Ancelotti's side looked dangerous on the counter, with Dries Mertens and Adam Ounas being denied only by some sensational last-ditch defending from Sassuolo. Simone Verdi had the clearest chance to open the scoring in the first period, but fired over from eight yards.
The deadlock was broken in the 52nd minute after a low cross from Pol Lirola wasn't dealt with by Allan, which left Domenico Beradi with a simple finish from five yards out to score his first Serie A goal since August.
Napoli looked to be running out of ideas, until a rare mistake in the Sassuolo defence from captain Francesco Magnanelli led to an excellent Insigne strike in the area, which saved Napoli from a second consecutive league defeat five minutes from time.
Key Talking Point
This was a disappointing performance from I Partenopei, as Carlo Ancelotti took a risk in making a radical switch in team selection and it didn't pay off. Napoli's focus this season will now be on winning the Europa League having fallen 18 points behind leaders Juventus.
What will most worry Napoli fans will be the clear lack of ideas the team showed against a side who had only won one game in ten matches, and while Mertens and Insigne did their best to create space and get in behind the defence, they were often stopped by either brilliant defending or poor decision making.
Napoli will need to play much better if they want to stay ahead of the two in-form Milan clubs and finish as Serie A runners-up, as Ancelotti's men seemed to be getting visibly more frustrated as the match went on.
Starting XI: Ospina (6); Malcuit (6), Chiriches (5), Koulibaly (7), Ghoulam (6); Ounas (5), Allan (4), Diawara (5), Verdi (5); Mertens (6), Insigne (7).
Substitutions: Luperto (5), Milik (6), Younes (5).
It's easy to see why Kalidou Koulibaly is one of the most wanted centre-backs in world football today. When others around were beginning to lose their heads around him, the Senegalese defenderwas a calming presence on and off the ball.
Although he was powerless to stop the goal, and while Insigne will take the plaudits for scoring the winner, Koulibaly was extremely solid and gave Sassuolo very little, particularly in the second half.
Napoli will travel to Austria on Thursday to face Red Bull Salzburg in the second leg of their Europa League last 16 match, with Ancelotti's men leading 3-0 in the tie. I Partenopei's next Serie A match will be against Udinese on Sunday at the Stadio San Paolo.