Napoli hold a 2-1 advantage heading into the break of a frenetic clash with Fiorentina tonight, thanks to a solo strike from Dries Mertens.

La Viola started brightly but were caught cold on 11 minutes by a ruthless Napoli counter, which saw Gonzalo Higuain pick out Jose Callejon with a clever diagonal pass.

Callejon made no mistake to break the deadlock, measuring a controlled volley into the far corner.

Napoli sat deep and looked dangerous on the counter, but were pegged back on 28 minutes as the hosts were awarded a spot kick following Federico Fernandez's push on Stefan Savic.

Giuseppe Rossi stepped up and confidently sent Pepe Reina the wrong way, drawing La Viola level despite fierce protests from the visitors with his ninth goal in 10 league games.

Juan Cuadrado struck the post in the very next attack as Fiorentina seized control of possession and territory, but Napoli were able to hit on the counter to go ahead at the break.

Belgian international Mertens did the damage on the break, beating three players to drive inside the penalty area and smash his first Napoli goal into the bottom corner.