Four goals in the opening 21 minutes helped Napoli to complete a 6-1 thrashing of Sassuolo on Saturday, a win that ensured Luciano Spalletti's side closed the gap on Serie A leaders AC Milan to four points.
Two defeats in their last three matches had seen Napoli fall behind Milan as the season draws to a close, making a win over mid-table Sassuolo imperative if Spalletti's team are to have any chance of securing a first Scudetto since 1990 this term.
The victory, however, was never in doubt as two headers from corners by defender Kalidou Koulibaly and Victor Osimhen put the hosts 2-0 in front inside 15 minutes in the Diego Armando Maradona Stadium.
It took until the 54th minute for Napoli to add a fifth as Mertens netted his second of the match, with Amir Rrahmani firing home the sixth 10 minutes from time to complete the rout.
Maxime Lopez's late consolation for the visitors mattered little as the emphatic victory moved Napoli on to 70 points, four behind Milan, who face Fiorentina on Sunday. Sassuolo stay 10th on 46 points.