Parma handed an ineffective Napoli a shock 2-1 defeat on Wednesday in a Serie A match in which all the goals came from penalties.
Napoli, who lost for only the second time since the season restarted, had 65% of possession on a sweltering evening at the Ennio Tardini but struggled to turn that into chances, a failing which has frustrated coach Gennaro Gattuso all season.
Tenth-placed Parma, who last won at home on Jan. 26 when they beat Udinese 2-0, ended a seven-match winless run.
Gianluca Caprari put Parma ahead in first-half stoppage time from a soft penalty after Mario Rui caught Alberto Grassi with his trailing foot.
Lorenzo Insigne replied in the 54th minute after a powerful Fabian Ruiz shot hit Grassi's arm at close range and the referee pointed to the spot after a VAR review.
But Parma won the game when substitute Dejan Kulusevski went over as he was challenged by Kalidou Koulibaly and the Swede converted the penalty himself in the 87th minute.
Napoli's record signing Hirving Lozano started only his 10th league game of the season and had a shot saved by Luigi Sepe in the second half in one of his side's few openings.
Substitute Amin Younes should have equalised in stoppage time but scooped his shot over the crossbar.
Napoli, who stayed seventh with 56 points, have made sure of a Europa League place by winning the Coppa Italia and are focusing on their Champions League last-16 match against Barcelona next month.