The most notable aspect of Dries Mertens’ sixth hat-trick as a Napoli player lay in the distances. None of his three goals on Friday evening against Empoli were struck from inside the opposition penalty area. The diminutive Belgian clearly has his range-finder perfectly set. Mertens now has seven goals from his last four games, a run of form which if not overdue, is a welcome hint that the 31 year old is approaching his best again, just as Paris Saint-Germain arrive at the San Paolo for what looks like a make-or-break evening for the Uefa Champions League prospects of either club. Mertens may never again have a run quite like the 39-goal, 12-month cascade he enjoyed from the beginning of December 2016, but right now his new manager Carlo Ancelotti can feel reassured that it was not only Mertens' special chemistry with the former Napoli tactician, Maurizio Sarri that stimulated his Midas touch. Mertens used to be commonly classified as a winger, skilful at turning past a marker with his low centre of gravity. He owed his late-career reinvention as a hugely effective forager and finisher through the middle of the attack when Sarri - who coached Napoli until his July move to Chelsea - was looking for ways to compensate after the prolific Gonzalo Higuain left Napoli for Juventus in the summer of 2016. He asked Mertens to realign his game. The shift was an inspired idea. It made Mertens suddenly the most potent marksman in a team constructed for attacking adventure. There are obvious distinctions between the Napoli of Sarri and the Ancelotti version. Possession is not so prized as a measure of superiority. Four-four-two, albeit flexibly interpreted, seems to have become the template formation rather than 4-3-3. The vastly experienced Ancelotti, owner of three Champions League titles, has also rotated his key personnel more willingly that his predecessor, who was a latecomer to top-division management. Sarri, who guided Napoli to three successive finishes in Serie A’s top three and pressed the serial champions Juventus for the domestic title through sustained periods, developed clear first XIs; his Napoli also leaned to the league campaign as a priority, the better to give a focus to the workload of his preferred first team. And Europe was a supplementary issue. Last season, Napoli finished third in their Champions League group, behind Manchester City and Shakhtar Donetsk; in none of the three, thrilling Sarri campaigns did his Napoli progress beyond the first new year knockout stage in either Champions League or Europa League. Ancelotti's programme of rest and recuperation has spread the load. The XI who lined up against Empoli registered team changes - totemic midfielder Marek Hamsik was rested - for the 14th time in as many matches. Evidently, the tinkering has not put a brake on momentum: Napoli are six games unbeaten since they lost 3-1 at Juventus at the end of September, including the positive overall balance so far in the heavyweight assignments that Champions League Group C set before Ancelotti. The <a href="https://www.thenational.ae/sport/football/watch-jurgen-klopp-says-liverpool-not-good-enough-in-defeat-to-napoli-1.776993">1-0 victory over Liverpool on Matchday 2 was a triumph of tactical initiative</a>; in the 2-2 draw at the Parc des Princes two weeks ago, Napoli twice took the lead against PSG, although Ancelotti regretted the leak of a stoppage time equaliser, for 2-2, from his old ally, Angel Di Maria, a footballer who he nurtured into a more rounded, more effective player when they won the European Cup together at Real Madrid. <strong>_____________</strong> <strong>Read more:</strong> <strong>Champions League talking points: <a href="https://www.thenational.ae/sport/football/family-friendly-barcelona-head-to-inter-milan-as-bashful-buffon-makes-return-uefa-champions-league-talking-points-1.788040">Bashful Buffon makes return</a></strong> <strong><a href="https://www.thenational.ae/sport/football/xherdan-shaqiri-left-out-of-liverpool-squad-to-travel-to-red-star-belgrade-1.788268">Xherdan Shaqiri left out of Liverpool squad to travel to Red Star Belgrade</a></strong> <strong>WATCH: <a href="https://www.thenational.ae/sport/football/watch-jurgen-klopp-says-liverpool-not-good-enough-in-defeat-to-napoli-1.776993">Jurgen Klopp says Liverpool 'not good enough' in defeat to Napoli</a></strong> <strong>_____________</strong> But Napoli also dropped points at Red Star Belgrade on Matchday 1, and it is that draw that effectively keeps the Italians from setting the pace in a taxing group. Tuesday's staggered kick offs mean PSG and Napoli will see how much catch-up is required on leaders Liverpool, <a href="https://www.thenational.ae/sport/football/xherdan-shaqiri-left-out-of-liverpool-squad-to-travel-to-red-star-belgrade-1.788268">who are in Belgrade for the early start</a> and could be four points clear at the top by 9pm Italian time. That would strengthen the idea that Tuesday's contest is part of a scrap for a single place in the knockout phase. Ancelotti promises to be "brave and to play with character against one of the best teams in Europe." They are one of his former champions, too, although significantly upgraded since he guided PSG to the 2013 Ligue 1 title. Kylian Mbappe and Neymar should start, although Edinson Cavani is likely to be fit enough only to make the substitutes bench at the stadium where he made his reputation as one of the finest centre-forwards of his generation. Cavani scored 104 goals in three seasons for Napoli before moving to France in 2013. Mertens is now just six shy of that tally for the club. He expects to reach his century imminently.