A spirited display could not prevent the game turning on its head following Juan Mata's opener in Italy, yet we remain very much in this Champions League tie.
At the Stadio San Paolo against a Napoli side that has played its best football on the European stage this season, and after surviving a couple of early scares, we went ahead through Mata's controlled volley, only to see the lead turn into a deficit before half-time.
First, Ezequiel Lavezzi stroked home from the edge of the area and then in injury time Edinson Cavani turned the ball home as Chelsea failed to deal with a whipped cross across the box.
The second half began brightly too, but optimism faded when Lavezzi converted his second of the evening just after the hour, and although Chelsea continued to look for a way back into the game, it was Napoli who could have added to the score when Ashley Cole, a substitute on for the injured Jose Bosingwa early on, cleared Christian Maggio's effort off the line.
So we return to London with a two-goal deficit, but knowing we can do damage against Walter Mazzarri's side. The scene is set for one of those famous nights at Stamford Bridge.
John Terry failed in his race to be fit for the game, and will now undergo an arthoscopy in order to determine the extent of his knee problem. Fellow injury doubt Ashley Cole was rated fit enough only for the subs' bench, meaning Jose Bosingwa started at left-back with Gary Cahill keeping his place in the centre of defence.
In midfield Andre Villas-Boas selected Florent Malouda ahead of both Frank Lampard and Michael Essien, with Raul Meireles chosen to sit deep, while Didier Drogba returned to lead the attack at the expense of Fernando Torres, who was among the substitutes.
Hosts Napoli were unchanged from their last Champions League group game, including defender Hugo Campagnaro who had been rated as a doubt.
Cahill, making his Champions League debut, had to be alert to cut out a clever Lavezzi reverse pass just into the second minute and shortly afterwards Petr Cech was quick off his line to punch clear with the diminutive Argentine giving chase.
It was the other South American that brought the first proper save from the Chelsea man however, Cavani the Uruguayan was found in space by Swiss midfielder Gokhan Inler, and with time to bring the ball down and pick his spot fired fairly straight and low, Cech blocking well with his feet.
Shortly afterwards Bosingwa required treatment and was forced to withdraw. On in his place came Cole with only 11 minutes on the clock.
After Walter Gargano won possession and fed Lavezzi, who in turn played in an offside Cavani, it looked as though the hosts were going to carve open the visitors at will and Maggio brought another cat-like stop from Cech before the 20-minute mark.
Chelsea were still getting forward and finding spaces in which to play on a sizeable San Paolo surface, but it was Napoli carrying all the threat, so imagine the surprise when Chelsea went in front before the half-hour.
A hurried passing move ended with Sturridge sending a loose pass into the home side's area, where Napoli captain Paolo Cannavaro scuffed his clearance to allow Juan Mata the opportunity to side-foot his volley home from 10 yards past the helpless Morgan De Sanctis.
Despite all the pressure, all the negative publicity and recent poor results, Chelsea were in front against the odds. But could we hang on to the lead?
In the 10 minutes following the goal, Napoli failed to fashion any more chances, and the Blues, in black, went close through a David Luiz header from Mata's corner. That chance came about after a Daniel Sturridge break, where had he crossed with his weaker right foot rather than trying to go outside his marker, he may well have found an unmarked Mata for a second goal.
But, just when Villas-Boas's men may have been gaining confidence, Lavezzi struck, turning on the edge of the box and sending two Chelsea men the wrong way before curling neatly into the bottom corner beyond Cech.
Wounded, Chelsea came back and Ramires found himself with a decent chance almost immediately, but fired over with his left foot having accelerated past a Napoli defender on the area's edge.
The midfielder would have been rueing his miss by half-time, as it was he who had conceded the throw-in that eventually led to Napoli's second goal.
The ball was eventually worked from left to right where the cross was not prevented, and nor would it be cut out in flight, allowing Cavani the simplest of bundled finishes at the far post.
Awful timing, yet having scored once Chelsea must surely have felt it possible again in the second period, so long as we could tighten up.
Four minutes into the second period Napoli's defence almost contrived to give us another slice of luck, a low corner diverted goalwards but cleared off the line before we could claim an equaliser.
Drogba, Mata and Malouda linked up to force a save, possibly a first of the game, from De Sanctis yet at the other end incisive passes were still too frequent to see, with Ramires and Meireles, forming a shield in front of the back four, too easily bypassed.
Mata fizzed another shot straight at De Sanctis while Lavezzi dragged a golden chance wide. Malouda then spurned a decent-looking volley before almost setting Drogba free with a lofted pass on the hour.
Chelsea were taking the game to Napoli, admirable in a hostile atmosphere, but the task became a whole lot harder on 64 minutes as the hosts doubled their advantage.
David Luiz was beaten by Cavani following a long ball from Campagnaro, and the forward then squared the ball to Lavezzi, taking an advanced Cech out of the game and allowing the Argentine to sweep home his second goal of the evening.
Villas-Boas called for Lampard and Essien, replacements with experience aplenty. With Meireles and Malouda withdrawn, Chelsea switched to a diamond midfield with Mata at its head, and Sturridge joined Drogba in attack.
This also prompted a slight change in approach, with more direct balls played up to Drogba in the hope that others would be able to support the target man. With men committed forward though we were more open than ever at the back.
Another Napoli break saw the ball squared by Marek Hamsik and Maggio poke towards goal only for Cole to be covering with a two-footed clearance right on the line. It was an intervention that may just have kept us alive.
Drogba turned over on the stroke of 90 minutes, and Lampard saw a long-range effort held by De Sanctis as we pushed for a late goal to tighten things up, but there was no breakthrough and so we return home needing a sizeable but not impossible victory.
Napoli (3-4-2-1): De Sanctis; Campagnaro, Cannavaro (c), Aronica; Maggio, Inler, Gargano, Zuniga; Hamsik (Pandev 81), Lavezzi (Dzemaili 73); Cavani.Referee Carlos Velasco Carballo (Spain)
Unused subs Rosati, Grava, Dossena, Fernandez, Britos.
Goals Lavezzi 37, 64 Cavani 45+1
Booked Cavani 39
Chelsea (4-2-3-1): Cech; Ivanovic, Cahill, David Luiz, Bosingwa (Cole 11); Ramires, Meireles (Essien 69); Sturridge, Mata, Malouda (Lampard 69); Drogba (c).
Unused subs Turnbull, Mikel, Kalou, Torres.
Goals Mata 26
Booked Meireles 40, Cahill 55