As has been the case in recent games under Thomas Tuchel, the Blues had plenty of first-half possession – but defensive errors almost proved costly more than once, with Edouard Mendy getting an early escape after a poor touch and Luis Suarez almost finding Thomas Lemar later on.
Despite those isolated moments, Atletico had few actual efforts, while Chelsea’s best chance came after a smart turn and strike from Timo Werner – but Jan Oblak wasn’t to be beaten at his near post.
Chelsea’s more adventurous outlook got the reward it deserved with 20 minutes to play, however, as Olivier Giroud reacted to send an overhead kick into the bottom corner – which he and his team were allowed to celebrate after a VAR review, overturning the on-pitch officials’ original call for offside.
Here are five things we learned from the game in Romania, Atletico’s home leg.
A very early booking in the first leg could yet prove costly in the second, as Mason Mount saw yellow within seconds of kick-off.
He has quickly become a key starter for Tuchel and was one of Chelsea’s players attempting to find the small gaps which did exist against the compact Atletico back line, so his absence will be felt.
Chelsea have options of course, with Hakim Ziyech and Christian Pulisic the duo most hopeful of involvement, but Mount is a big tactical cog as well as a technical one, with his work-rate always an important aspect that the Blues rely on in big, tight matches.
Jorginho following him into a yellow card suspension won’t help, either.
So many of Tuchel’s first games as Chelsea boss have followed a particular pattern: dominance of possession, lots of the ball in the opposition half, but frequently unable to create actual clear-cut shooting chances despite the territorial advantage.
Games have been close, or frustrating, as a result of the inability to turn that use of the ball into goals and it was again the same here – though this time by the design of Atletico, rather than Chelsea themselves imposing their style on the match.
Right from the start it was apparent that Atleti would take a typical Diego Simeone approach: sit in with a very well-drilled shape, pack out the penalty box to close off passing lanes, and wait for the chance to flood forward.
While the approach was no surprise, it definitely didn’t pay dividends on this occasion for Atletico.
Los Rojiblancos failed to have a shot on target all match and the front three committed more fouls than they had combined shots – a pretty clear indication of their plan.
Late on, after the goal, it proved impossible for them to switch gears and start to trouble Chelsea in attack, with the frustration switching from away side to home with exactly the same approach on show.
There cannot be any complaints, only an acceptance that the plan backfired woefully and the second leg will need a very different ploy.
The Blues rotated early in the season at centre-forward: Timo Werner, Tammy Abraham, Olivier Giroud. Under Tuchel, rather than Frank Lampard, the German forward looks to be an exclusively left-sided support option, other than late on in matches.
But the No. 9 role is up for grabs. Abraham has started some, been subbed off at half-time, seen Mason Mount take that role as a withdrawn option between split forwards…and now seen Giroud stake a very real claim to be first-choice once again.
The French forward didn’t have a lot of chances, but occupied defenders well, kept making the runs to beckon crosses toward him and, crucially, was clinical when his half-chance came along.
That’s something Abraham hasn’t yet been able to replicate often enough and this strike, an away goal in Europe, could prove even more vital.
It’s too early to be considering what Chelsea can achieve this season under Tuchel, but there can be no doubts that they have twin objectives which can be considered both achievable and a step forward from last season.
Lampard took Chelsea into the top four, but not beyond this stage – they were outclassed by Bayern Munich, understandably.
We’ll never know if Lampard would have been able to devise a tactical plan to beat Atletico, but the evidence of this season and his demise would certainly be against the theory – but Tuchel is halfway there.
He won’t want a top-four finish and a run into the last eight to be the sum of his ambitions, but it’s a great start considering he has needed to hit the ground running halfway through a campaign of relative under-achievement.