Paris Saint-Germain's start to the Ligue 1 season has been both unusual and unexpected. After six games, they remain unbeaten, yet they lie six points off high-flying Marseille in a lowly sixth position. Four draws have cost them dearly.
Including a further draw away to Ajax in the Champions League, Laurent Blanc's side have now taken just a solitary point from four of their past five games, with the exception being a dramatic 5-0 league win over third-placed Saint-Etienne.
With PSG, nobody doubts the talent or potential, but something is not quite right at the present time. Perhaps, then, the return of influential captain Thiago Silva will help inspire the side to better performances in the weeks ahead?
Thiago's return, though, creates an interesting dilemma for Blanc. He has seen his current defensive pairing of David Luiz and Marquinhos perform well together, with PSG having conceded just four goals in six games this season.
However, what will make coming decisions even more intriguing is that it is 20-year-old Marquinhos who has arguably been the most assured of the Parisiens' back four. With WhoScored.com statistics showing him averaging 2.2 tackles, 2.8 interceptions and 4.2 clearances per game, he is comfortably the highest defensive contributor.
As Jonathan Johnson writes for ESPN FC, he is a far more mature presence than last season and has been a real bright point of the campaign. Writing for Bleacher Report earlier this week, Johnson even ponders whether it will be Thiago who will struggle to earn a place in the side in the weeks ahead.
It is an intriguing situation for the three Brazil internationals, but there can be no doubt that it is the youngster Marquinhos who will be feeling the least pressure of the three. For £40 million signing David Luiz, however, a career-defining season lies ahead.
At Chelsea, for all the trophies that he won, it is fair to say the Brazilian never fully won over his doubters and—while his reputation has always been greater in Brazil—his woeful end to the World Cup has done much damage to his standing.
Having moved for such an enormous fee, the onus is now on Luiz to justify that outlay.
There can be no excuse for failure either. At PSG, he will likely be paired with a defender he knows intimately in Thiago Silva, in a league where his side should not come under regular intense pressure. His task will be to step up to the plate in big games when the Parisiens are no longer the dominant force.
The talent of the Vitoria academy product has never been doubted. Technically he is strong in possession and in his defensive work, while his natural physical attributes are ideal for a top-class central defender. It is in his positioning, concentration and decision-making that doubts have lain.
Alongside Thiago, though, he has generally been excellent for his country and, in that respect, it is perhaps no surprise that Brazil and Luiz's meltdown against Germany earlier this summer came in the absence of his long-established partner. If he can settle into the kind of form he had been showing when alongside his compatriot, PSG will not worry again about the fee they paid.
All truly top-level players have a season in which they are imperious, and this must now be Luiz's. If he cannot hit such heights, he may just find that the incredibly assured presence of Marquinhos is quickly preferred at the heart of the defence. He must make his case and do so quickly.
With Thiago now in his 31st year, the stage is set for Luiz and Marquinhos to take over the reigns in the long term, but there will be issues if one finds game time hard to come by over the next two (or maybe more) years.
Earning and retaining a regular starting berth now, then, is crucial to how the future may play out. And for David Luiz, this spell in Paris could define how his career among football's elite is regarded. It is time to put the jokes aside and focus on ensuring he takes a long-awaited next step in his development this season.
If he can do so, a place at the high table of world football's best defenders awaits. However, that has now been the case for some time, and the clock continues to tick.