Juventus recovered from their Champions League defeat at Chelsea to add to the pressure on Napoli coach Edoardo Reja with a win at Olympic Stadium.
Claudio Marchisio scored in the 44th minute to take the Bianconeri to within six points of Serie A leaders Inter Milan, who host Roma tomorrow night.
Napoli, in contrast, are still searching for their first win in eight league matches and remain stuck in mid-table with Reja clinging onto his job by a thread.
Juventus coach Claudio Ranieri fielded Alessandro del Piero and David Trezeguet in attack for the first time this season with Sebastian Giovinco giving veteran winger Pavel Nedved a break.
The attacking formation signaled Ranieri's intention of getting in an early blow on league leaders Inter 24 hours before they host Roma in a tough fixture at the San Siro.
Del Piero had the home team's first chance in the 10th minute when he cut in from the right and forced Nicolas Navarro to make the save in two attempts.
A cross from Del Piero in the 15th minute then set his strike partner Trezeguet up for a chance from point-blank range.
Navarro made a quick reaction save, but the ball still spilled out to Giovinco, who had the whole of the goal to aim at but seemed to either slip or lose his balance as he blazed the ball over the open goal.
Del Piero was involved in everything early on and one of his trademark direct free-kicks from 25 yards forced Navarro into another save as it started to dip under the crossbar.
Napoli had to wait until the 38th minute before their first sight of goal, which fell to Marek Hamsik, whose shot from a tight angle was deflected behind by Juventus goalkeeper Gianluigi Buffon.
Juve were the most threatening side in the first half, and they got the goal they deserved just a minute before the interval, although luck certainly played a part.
Marchisio's 25-yard shot was heading wide to the left of the goal before it took a wicked deflection off Fabiano Santacroce to wrong-foot Navarro and curl into the opposite corner.
Napoli responded well in the second half with Hamsik's volley from the edge of the area keeping Buffon warm.
Ranieri reacted by removing Giovinco to bring on the more defensive-minded Hasan Salihamidzic before Nicola Legrottaglie limped off with a worrying knee injury and Olof Mellberg took his place.
The visitors kept looking for an equaliser and thought they had got it two minutes from time when Ezequiel Lavezzi beat Buffon at his near post, but play had already been halted for a dubious offside decision against Paolo Cannavaro.
Juve managed to hold on for a crucial three points which could open up the race for the Scudetto once again.
