Beaten 1-0 by potential title rivals Inter in Milan, the leaders move on to Genoa this weekend, where they encounter a Samp side celebrating just their second league win this term.
Match preview
Losing their status as the only unbeaten team throughout Europe's top five leagues, Napoli resumed competitive action following the long winter break on Wednesday, with a 1-0 defeat at San Siro.
Off the pace for much of the match, Luciano Spalletti's side were ultimately beaten by Edin Dzeko's second-half header; ending a superb streak of 11 league wins on the spin and seeing their lead at the Serie A summit cut to five points from second-placed Milan.
Still seeking a first Scudetto for more than 30 years, Napoli found themselves out-thought and outmanoeuvred by Inter, who could have scored more, and the Nerazzurri now join both their city rivals and Juventus on the trail of the title.
Set to lock horns with Juve next Friday night, the Partenopei will be keen to revert to winning ways in-between their two titanic tussles at the start of 2023, so meeting Sampdoria may prove well-timed in that regard.
Former Samp coach Spalletti leads a club which has won each of their last seven Serie A matches against Sunday's hosts, having scored 47 times in the sides' last 18 top-flight meetings - an average of 2.6 goals per game.
How Napoli now respond to their first real adversity of the season could shape their Scudetto hopes over the coming months, so victory at Marassi is vital against struggling opponents.
Sampdoria have lost six of their last seven home fixtures against Napoli - as many defeats as in their previous 28 - which outlines the gulf in stature between the two clubs during recent years.
While their Campanian counterparts battle it out for glory at the sharp end of Serie A, Samp are reduced to a second successive relegation scrap and were in deep trouble as the action paused for Qatar 2022 to take place.
With only one win to their name from the first 15 rounds, the Ligurians occupied 19th place at Christmas, but an unexpected victory on Wednesday offers a glimmer of hope for Dejan Stankovic's side.
Their 2-1 success at Sassuolo - courtesy of first-half strikes from Manolo Gabbiadini and Tommaso Augello - brought Sampdoria's tally of away wins up to a modest two, but they have fared even worse on home soil this term. Having taken no points from their last five home matches - and they have never lost more in a row during their time in Serie A - the pressure is now on to halt that run.
Even holding Napoli to a draw would provide another boost to morale in the camp, and an unlikely win would represent the first time Samp have won their first two calendar-year fixtures since 1997, under Sven-Goran Eriksson.
Current coach Stankovic, still mourning the recent loss of countryman and mentor Sinisa Mihajlovic, will now lead his men out at Marassi on a day of raw emotion and reflection, following the untimely death of club legend Gianluca Vialli, who played a major role in the Blucerchiati's fabled title triumph of 1991.
Sampdoria Serie A form:
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W
Napoli Serie A form:
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Napoli form (all competitions):
L
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Team News
After being ruled out of three games before the break with a back problem, Napoli winger Khvicha Kvaratskhelia returned in Wednesday's clash with Inter, but is now a doubt for the leaders' trip to Genoa.
Having been substituted at San Siro, the fleet-footed Georgian subsequently missed training, so Eljif Elmas is on standby to deputise.
Up front, Giacomo Raspadori is pushing to start in support of top scorer Victor Osimhen, who has previously scored three Serie A goals against Sampdoria - one every 57 minutes on average.
Meanwhile, Samp's revamp of their attacking department has seen misfiring veteran Francesco Caputo loaned to Empoli and Dutch forward Sam Lammers arriving in return, and the latter should partner Manolo Gabbiadini once again. The Italy striker scored his first Serie A goal since August last time out, but has netted just twice in 10 meetings with former club Napoli.
Further boosting Dejan Stankovic's final-third options, Filip Djuricic returns from suspension on Sunday, while Harry Winks and Morocco midfielder Abdelhamid Sabiri both returned to full training this week but are not likely to be involved just yet.
Fabio Quagliarella, Andrea Conti and Ignacio Pussetto remain sidelined by injury for the hosts, who should line up with a three-man defence featuring another recent signing, Bram Nuytinck.
Sampdoria possible starting lineup:
Audero; Murillo, Colley, Nuytinck; Bereszynski, Rincon, Villar, Verre, Augello; Lammers, Gabbiadini
Napoli possible starting lineup:
Meret; Di Lorenzo, Kim, Jesus, Olivera; Anguissa, Lobotka, Zielinski; Politano, Osimhen, Elmas