Napoli moved into fourth place in Serie A after goals from Marek Hamsik and Edison Cavani at Lecce kept their prospects of Champions League football alive.
The visitors scored at the start of either half to go within a point of third-placed Lazio, who surprisingly lost at Novara, while Udinese also slipped up at home to Inter Milan.
Hamsik handed his side the lead in the fifth minute, with Cavani doubling the lead six minutes after the break as Lecce failed to make their own chances count.
Gokhan Inler created the opener after winning a free-kick in dangerous territory, with Hamsik on hand to lash into the top corner from outside the penalty area.
Little else happened for the next 15 minutes, after which came a flurry of attempts on goal.
Juan Cuadrado and David Di Michele tried their luck for the hosts, but both failed to hit the target by a distance.
Cavani responded in kind for Napoli, thrashing well wide.
With 36 minutes gone Lecce's Luis Muriel produced a better effort, Morgan de Sanctis doing well to make the save, while Blerim Dzemaili went close at the other end three minutes before the interval.
De Sanctis produced another top save just after the resumption to deny Gennaro Delvecchio and soon after it was 2-0 to Napoli.
Inler was again the provider, making the decisive pass after a brisk counter-attack and finding Cavani, who finished coolly.
Although there were more than 40 minutes to play, that was the last genuine chance, with Napoli adding only a soft Cavani effort and a decent low shot from Juan Camilo Zuniga six minutes from time.
Lecce were unable to do any better, Delvecchio and Daniele Corvia both missing the target as they attempted to drag the home side back into contention.