The Blues were stunned by bottom-placed Crystal Palace, while their opponents went down to table-toppers Napoli, but it is the one-time winners of this competition who are better positioned in Group C.
Following their heroics at the Wanda Metropolitano last time out in Europe, when pulling off one of the finest results for an English side in the competition's recent history, Chelsea appeared to be over their early-season wobble.
Misplaced talk of a so-called crisis at Stamford Bridge looked to be wide of the mark, as a few disappointing results in the opening five weeks of the campaign soon became three impressive victories on the bounce, including that win away to Atletico Madrid.
Since nicking a late win in the Spanish capital, though, Chelsea have lost back-to-back Premier League games to sides at both ends of the table, following up a 1-0 defeat at home to Manchester City with a shock 2-1 reverse at Crystal Palace either side of the international break.
Those defeats have left the Blues nine points off the pace and with it all to do if they are to defend their title, but their hopes of success on the continent - where they have recent history of beating all the odds - do appear to be a little rosier at this moment in time.
As well as edging out Atletico, Chelsea also crushed Azerbaijani minnows Qarabag FK 6-0 in the opening round of fixtures to leave them top of Group C on six points from six, meaning that three more points this week could put them on the brink of progression to the knockout stages.
That is the minimum target for the English champions, of course, having missed out on a place in UEFA's showpiece competition last time out, and they certainly know how to get the job done as they have finished top of their group in their last three Champions League appearances.
Only once have the West London club failed to make it as far as the last-16 stage, in fact, when becoming the first defending champions to exit at the group phase in 2012-13, before going on to win the secondary competition in the Europa League.
One defeat in their last nine home European matches suggests that the Blues can get the job as good as done on Wednesday night, which would go a long way to helping Antonio Conte avert this latest 'mini crisis'.
Recent form in Champions League: WW
Recent form (all competitions): DWWWLL
A Lorenzo Insigne strike in the first half - his 100th career goal - proved enough to earn the Partenopei all three points at the Stadio Olimpico, while at the same time putting an end to the hosts' five-match winning run.
The Giallorossi had not lost in any of their last seven heading into that huge showdown, in fact, though after failing to net late on they now find themselves nine points adrift of their opponents, albeit with a game in hand still to play.
Much like Chelsea, though, Roma are looking good value to progress through in Europe after following up their goalless opening-game draw against Atletico with a 2-1 win away to Qarabag a few weeks back to leave them in second place.
With a double-header to come against Chelsea and a trip to Atletico later in the campaign, however, Eusebio Di Francesco's men have a big task on their hands staying in that qualification spot after all six rounds of fixtures.
Roma hardly boast the best of records in the Champions League, either, going seven without victory - including qualifiers - prior to seeing off Qarabag through Kostas Manolas and Edin Dzeko goals inside the opening 15 minutes at the Azersun Arena in Baku.
The Giallorossi have also won just two of 15 games away to English opposition, losing nine of those, but they did earn a 1-1 draw against Man City on their most recent visit when Francesco Totti became the competition's oldest scorer in 2014.
Club legend Totti may no longer be around, meaning that it is down to the current crop to step up to the plate and provide some inspiration for this tricky-looking trip to the English capital.
Recent form in Champions League: DW
Recent form (all competitions): WWWWWL
Conte claimed after the defeat to Palace that his side would always find life difficult without a trio of their first-team players, each of whom are likely to miss out once again on Wednesday.
Danny Drinkwater and N'Golo Kante appear to be a couple of weeks away from a return, while top-scoring striker Alvaro Morata is still battling a hamstring problem which, on the plus side, is not as serious as initially thought.
To make matters worse for the hosts, though, wing-back Victor Moses could now be facing a spell on the sidelines with a hamstring problem of his own, so Davide Zappacosta may enjoy an extended run in the side.
In terms of the visitors, Di Francesco would love to have former Roma player Antonio Rudiger back in his ranks as he faces a similar sort of injury crisis for this huge showdown.
The latter two have a chance of returning, which in the case of defensive midfielder Strootman would be a major boost, providing a solid platform for Radja Nainggolan - constantly linked with a Premier League move in recent years - to get forward.
Chelsea possible starting lineup:
Courtois; Cahill, Luiz, Azpilicueta; Zappacosta, Fabregas, Bakayoko, Alonso; Pedro, Hazard, Morata
Roma possible starting lineup:
Alisson; Bruno Peres, Juan Jesus, Fazio, Kolarov; De Rossi, Strootman, Nainggolan; Florenzi, Perotti, Dzeko
Head To Head
These two sides have faced off on four previous occasions, most recently in the group stage of the 2008-09 Champions League.
The Blues came out on top 1-0 in the home game and lost 3-1 at the Stadio Olimpico, with John Terry netting in both fixtures.
While the Giallorossi have won just two of their 15 away games against English opposition, Chelsea have lost two of nine against Italian sides on home soil.
We say: Chelsea 2-1 Roma
Both teams may have injury issues to contend with, but there will still be plenty of quality on display at Stamford Bridge for one of the standout ties of the round. Chelsea boast a good record on home soil in this competition, losing just one of nine, and they should have too much for Roma on Wednesday night.