The Italian club, like their opponents, looked shaky in defence but were clinical enough to eventually win their Round of 16 first leg comfortably at the Stadio San Paolo despite falling behind to Juan Mata's 27th-minute opener.
It was an open, attacking affair with both sides giving each other so much space and time to go about creating scoring chances and it was Walter Mazzarri's men who made the most of it with Ezequiel Lavezzi scoring a brace and Edinson Cavani netting his customary goal against English clubs to make it four in three matches this campaign following his three against Manchester City in the group stage.
Just before the half-hour mark, Chelsea cracked open the Napoli defence when Daniel Sturridge's low pass to the top of the area took a terrible bounce as skipper Paolo Cannavaro went to clear with Mata reacting well to slot home the wayward ball to make it the first goal for the Blues in every Champions League game this season.
Seven minutes prior to half-time, however, Lavezzi netted his first goal in the competition in brilliant fashion when he was given too much time to pick his spot and curl home past Petr Cech from about 20 yards after poor marking from the Chelsea midfielders.
In injury time of the first half, Napoli clawed their way in front when Cavani got on the end of Gokhan Inler's perfectly weighted ball to cleverly shoulder home from the back post to put his side ahead, giving Andre Villas-Boas plenty to think about during the break.
Just as it looked like Chelsea would fight back to level at 2-2, Napoli grabbed a third in the 65th minute when David Luiz failed to deal with a ball directed at Cavani, allowing the Uruguayan to compose himself and tee up Lavezzi who fired home past a hapless Cech for his second of the match.
There were chances galore throughout, with the best early ones coming in the 10th minute when Cavani found himself in acres of room onside from Walter Gargano's chipped ball but saw his rifled attempt saved by the legs of Cech.
About ten minutes later, Cech came up with another vital save when Lavezzi had played in Christian Maggio whose angled attempt was flicked further across goal by the hands of the Blues gloveman.
Both keepers had a number of comfortable saves to make as either side tested their luck from range with regularity before Chelsea defender Ashley Cole, who had earlier come on for the injured JoseBosingwa, was able to take inspiration from the glovemen to make a goal-line clearance from Maggio's shot which would have further sunk the Blues.
The loss leaves Chelsea with just one win from 11 European matches in Italy - their last victory coming against Lazio in 2003 - whilst Napoli have not been beaten at home in Europe since 1994 ahead of the return leg at Stamford Bridge on March 14.
UEFA Champions League Round of 16 - first leg
Stadio San Paolo, Naples - 54,000