With the news that Romelu Lukaku was being benched for Chelsea's meeting with Lille on Tuesday, all eyes were on his replacement, Kai Havertz.
The silky German was to be the lab rat for the latest of Thomas Tuchel's experiments on a mission to determine whether Lukaku was responsible for the Blues recent malaise, or whether Chelsea as a whole needed to take the blame.
While it's impossible to get a true answer for that after just one game, there's no denying that Havertz made a persuasive argument for the former almost immediately.
From kick-off, Havertz looked on it. He could have scored with his third touch of the ball after just four minutes - firing his strike over the top when it looked easier to score - and then saw another great chance saved before eventually opening the scoring with his eighth touch.
Just eight minutes in, Havertz had eclipsed Lukaku's touch tally from the Crystal Palace victory and, most importantly, he had actually made an impact on the scoresheet. This was the most impetus we have seen from a Chelsea side in God knows how long.
All game, it was clear just how much this Chelsea squad preferred playing alongside Havertz. The German was roaming around more than Lukaku, drifting wide and dropping deep to bring those around him into the game.
Now, it's not as if Lukaku doesn't move. He made some excellent runs against Palace and deserved far more than his seven touches, but he just appears to be on a completely different wavelength to his team-mates.
On the other hand, Havertz's movement felt organised. When he would move towards the front post, the cross would come in. When he dropped deep, teammates were looking for him. Chelsea seemed to know where Havertz was at all times, and the freedom that gave them was abundantly clear.
Christian Pulisic and Hakim Ziyech made runs off Havertz and got themselves into the box. N'Golo Kante flew forwards and added to the fun as well. Chelsea's squad look as though they need somebody with Havertz's fluidity to work with.
Havertz seems in sync with those around him and the squad almost seem to be expecting the same movements from Lukaku, who is obviously a wildly different player.
Unfortunately for Lukaku, this game hasn't helped his case among fans. Many supporters blame the towering striker for Chelsea's recent struggles, and having seen what the Blues can do without him, that argument has only been fuelled.
However, you need to dig a lot deeper to understand the bigger picture. For example, Pulisic had his best game in ages here and helped make Havertz look good too - is that because Lukaku wasn't there or purely a coincidence? You can't tell after just one game, but football infamously doesn't wait for players to prove their points. Not expensive ones like Lukaku, anyway.
So, as far as the 'who's to blame' debate goes, we still don't have an answer.
This system doesn't appear suited to someone of Lukaku's skillset, but Lukaku hasn't been doing enough to get involved either. It does have the feeling of a match made in hell.
What we do know, however, is that Chelsea can be very impressive in attack when they get all their pieces in place. The Blues can control a game, make chances and pick their way through a defence, and they can make it look pretty easy when they want to.
In the short term, and specifically for Sunday's Carabao Cup final against Liverpool, Havertz might be the answer.