Algerian forward Adam Ounas gave second-placed Napoli a fourth-minute lead, cracking home after awful defending by Sassuolo, before being replaced early in the second half by Insigne.

Italy international Insigne made sure of the points with a terrific finish in the 72nd minute, collecting the ball two yards outside the penalty area, widening his stance and curling a shot into the far top right corner. Sassuolo had Rogerio sent off later on.

Mauro Icardi scored twice as Inter Milan climbed to third place with a 2-1 win against SPAL.

Inter's sixth victory in a row across all competitions, and fourth in succession in Serie A, was hard earned.

Icardi made an early breakthrough in Ferrara and then slotted a precise finish for a 79th-minute winner after SPAL had briefly drawn level through Alberto Paloschi. SPAL's Mirco Antenucci also missed a penalty.

Gonzalo Higuain scored twice as AC Milan were 3-1 winners against Chievo at the San Siro. He netted in the 28th and 35th minutes, before Giacomo Bonaventura added a third for the Rossoneri in the 57th minute. Sergio Pellissier grabbed a consolation seven minutes later for struggling Chievo.

Ciro Immobile prodded a 38th-minute winner as Lazio edged out Fiorentina 1-0 in Rome, while all the scoring came early at the Stadio Luigi Ferraris where Genoa were beaten 3-1 by Parma.

Hosts Genoa nudged ahead with Krzysztof Piatek's seventh-minute effort, but Parma were soon level through Luca Rigoni, then ahead thanks to Luca Siligardi. They moved 3-1 in front after 31 minutes when Fabio Ceravolo scored, and it stayed that way.

Lorenzo Tonelli scored a thumping header as Sampdoria won 1-0 at Atalanta.

- PA