Edinson Cavani failed to register his 100th Serie A goal but Napoli kept in touch with league leaders Juventus courtesy of a third consecutive victory.
The Uruguayan was primed to bring up a century of goals in the Italian top flight, with his former club Palermo the likely victims, but instead Christian Maggio proceeded to open the scoring.
Cavani continued to have an off day but Gokhan Inler and Lorenzo Insigne spared him any embarrassment by ensuring a third straight defeat for Palermo, who are now four points from safety.
Goran Pandev managed to pick out Cavani through a downpour of rain at the San Paolo, the imposing Uruguayan shaping to shoot only for Samir Ujkani to snatch the ball off his feet.
Palermo responded well, debutant Andrea Dossena seeing his first-time shot parried to safety by Morgan de Sanctis.
Santiago Garcia did well to diffuse a fine passing move between Cavani and Marek Hamsik but moments later the Napoli striker was prostrate in the box and demanding a penalty.
His calls fell on deaf ears, though, and Cavani was denied the chance to score his landmark goal from the spot.
Palermo went close in the 27th minute as Michael Morganella whipped Anselmo's pass across the goalmouth, but it was Napoli who made the breakthrough.
Hamsik saw his corner rebound high into the box, with Maggio rising highest to head the Azzurri into the lead on the half-hour mark.
Napoli had enjoyed a touch of good fortune for their opener but there was no denying the quality of Inler's goal when it came four minutes later.
The Swiss midfielder exchanged a couple of delicate passes with Hamsik, the latter streaking onto the left wing before sending the ball back into his team-mate's path.
Inler bombed forward to slam the ball beyond Ujkani and Palermo were firmly under the cosh.
Edgar Barreto rattled the crossbar with a sweetly-struck free-kick but the Rosanero would not reply before the break.
Hamsik missed a trick as play resumed and Palermo substitute Fabrizio Miccoli almost made him pay with a shot on the turn, but his radar malfunctioned.
The Slovakian had looked most likely to register the third goal and he never came closer than in the 56th minute, having been freed up by Juan Camilo Zuniga.
His first shot rebounded back into his path and he pulled the trigger again, but Maggio was unable to tuck home the wild deflection and the move broke down.
Walter Mazzarri was encouraged by Napoli's dominance but shook things up by throwing Insigne into the action on 68 minutes, and the move paid dividends.
The young Italy international had been on the pitch five minutes when he sealed a comfortable win by driving Inler's cross just under the bar and into the net.