MILAN Napoli continued their free-scoring season by thumping Torino 5-0 away in Serie A on Sunday while hapless Inter Milan lost again in front of disgruntled fans at San Siro.
Inter's 2-1 loss to Sassuolo was their fourth defeat in a row and most of their hardcore fans walked out in protest in the 25th minute, leaving a banner on the curva Nord saying they had "gone to lunch".
With two rounds of matches to play after Sunday, Juve lead with 85 points, five ahead of Napoli, with AS Roma a further two points behind. Juventus were away to Roma in the evening game, needing one point to wrap up their third successive title.
Jose Callejon gave Napoli a seventh-minute lead at Torino, sending an angled drive past Joe Hart and into the far corner.
Lorenzo Insigne added a second goal on the hour, then Mertens surprised Hart at the near post to score the third before Callejon slid in Faouzi Ghoulam's cross for his second of the match.
Piotr Zielinski put the finishing touch as Napoli took their tally for the season to 86 goals.
Inter, who sacked coach Stefano Pioli on Tuesday, did no better under caretaker Stefano Vecchi as Pietro Iemmello scored either side of halftime to put Sassuolo 2-0 ahead.
Eder pulled one back for Inter but it did little to inspire his team or quell the protests.
There were bizarre goals elsewhere.
Chievo were left fuming when goalkeeper Stefano Sorrentino lost his boot during a clash on the byline but play was waved on and Fabio Quagliarella scored into an empty net to put Sampdoria ahead.
Roberto Inglese volleyed home early in the second half to give the Flying Donkeys a 1-1 draw.
Genoa lost 1-0 at relegated Palermo when their goalkeeper Eugenio Lamanna caught a harmless Andrea Rispoli header under the crossbar but stepped backwards into his goal and took the ball over the line with him.
Genoa's defeat left them with 33 points, only two ahead of Crotone in the relegation zone with Empoli sandwiched in between.
Crotone continued their bid for a great escape by beating Udinese 1-0 with a goal by Marcus Rohden while Empoli lost 3-2 at Cagliari. Palermo and Pescara are already down.
(Writing by Brian Homewood in Berne; Editing by Clare Fallon)