Rome: Argentina striker Gonzalo Higuain scored his sixth goal in four consecutive games to secure a precious 1-0 win away to Fiorentina that moved Rafael Benitez`s side up to third in Serie A on Sunday.
However Napoli`s win was tempered by winger Lorenzo Insigne suffering a suspected knee ligament injury.
A club statement said Insigne, who was forced off in the 25th minute and replaced by Dries Mertens, had suffered a "distortion of the right knee involving the ligaments.
"Tomorrow (Monday) morning he will undergo a scan."
Higuain beat Fiorentina `keeper Neto with a powerful shot from close range on the hour of a thrilling encounter at the Artemio Franchi stadium, where Mario Gomez saw a late header come off the crossbar as the hosts pressed for a late equaliser.
Higuain took until the eighth game of the season to get off the mark for Napoli, scoring a hat-trick in a 6-2 win over Verona.
But he has hit the net in three successive games since to sit on six goals for the season, two behind table-topping teammate Jose Callejon, who saw Juventus striker Carlos Tevez pull level on eight goals with a brace in a 7-0 rout of Parma earlier Sunday.
Napoli now sit seven points behind defending champions Juventus but only one behind Roma, who host Torino in one of two late games on Sunday.
Sampdoria dropped to fourth, one point behind Napoli, after being held 2-2 by Milan in Genoa on Saturday, with Lazio a further point adrift in fifth after a 2-1 slip-up away to promoted Empoli.