Second-half goals by Colombian striker Duvan Zapata and playmaker Marek Hamsik guided Napoli to a 2-0 win over Sassuolo in their Serie A clash on Monday and saw the victors close the gap on second-placed Roma.

Napoli -- who are just three points in arrears of Roma who have dropped points galore with a run of eight draws in nine games -- managed to hold on despite Belgian midfielder Dries Mertens being sent off only six minutes after coming on as a substitute for a tackle from behind on Simone Missiroli.

For Napoli it was their fifth win in six matches and while the 12 point gap to leaders and defending champions Juventus might appear insurmountable the three point gap with Roma for the second automatic Champions League spot certainly is.

Zapata more than made up for the absence of the suspended Argentinian international striker Gonzalo Higuain in scoring the opener in the 61st minute.

Slovakian star Hamsik, who had set up the first, doubled the lead nine minutes later with a smartly taken curling effort from inside the area after the Colombian had returned the favour by laying the ball back to him.

Mertens' dismissal came soon afterwards but Napoli still ahd enough of an edge in class to hold on to their lead over a Sassuolo side that could yet get sucked into a relegation battle.

Monday's late game sees relegation-threatened Cagliari host Inter Milan, who are only three points and a place above Sassuolo.