Victor Osimhen scored for the second consecutive league game but it was not enough as Napoli were held to a 2-2 draw by Frosinone.
Osimhen gave Napoli the lead for the second time in the game three minutes after the hour mark.
It was the forward’s 13th league goal of the season for the Partenopei.
The Nigeria international turned in from six yards after Kvicha Kvaratskhelia’s shot was deflected onto his path.
The result put a dent on Napoli’s aspiration of qualifying for the UEFA Champions League.
The reigning Serie A champions remain in eighth position with 49 points from 32 games.