Thomas Tuchel has had two dates in his head since the end of August. As soon as the Champions League group stage draw was made in Monaco and the fixtures of the competition announced, the PSG manager earmarked this week as the moment of truth during the first part of his first season in Paris.
Napoli at home at the Parc des Princes on Wednesday and Marseille away at the Stade Velodrome on Sunday: it doesn't get any bigger than this.
With no arrogance, the German coach knew that the season could go very well until then and that this week will be his and his team's first genuine challenge. Of course, there has already been a trip to Anfield and a defeat against Liverpool (3-2), but Tuchel dismissed its importance because it was the first Champions League encounter of the season. There has also been the visit of Lyon in Ligue 1, but Kylian Mbappe was on another planet that night and PSG were a class apart, winning 5-0.
Therefore, the two games coming up are without a doubt the biggest of the season so far, albeit for different reasons. We will find out if the good things we've seen until now in this campaign like the high press, the intensity with and without the ball, the tactical flexibility, the blossoming Neymar/Mbappe partnership or the new lease of life for Angel Di Maria can take PSG to two convincing victories.
Napoli is surely the most important match in terms of points and context. In a Champions League group that's proving really tight already, with the Italians on four points and Liverpool and PSG on three, the Parisians can't afford to trip up at home on Wednesday. They will then have two away games in Naples and Belgrade against Red Star while hosting the Reds in between those two trips. The Champions League is the main objective for PSG's season.
Tuchel and his players need to put a marker down as Carlo Ancelotti returns to the Parc des Princes with his new team. Tactically, it will be an interesting battle as the Sicilian side are far less dogmatic than under Maurizio Sarri but have been impressive, particularly in their win against Liverpool three weeks ago.
Another tantalising note is that the game serves as Edinson Cavani's reunion with his former team as well. Despite a good ratio of goals scored to games played (six in nine), the Uruguayan is struggling to find his place amid the burgeoning Neymar/Mbappe bromance. This would be a good game for Tuchel to find a way of involving his central striker more in his team's collective expression. On Wednesday, PSG will be tested for sure. Another Champions League loss would look bad for Tuchel and certainly hurt his credentials as well as PSG's hopes of making a deep, competitive run in Europe.
Then will come Le Classique on Sunday. It will be Tuchel's first taste of this bitter rivalry between Marseille and Paris, between the South and the North, between the second biggest city and the capital.
It will also be Neymar's second visit to the Velodrome. Last season, he was sent off and Cavani saved the day with a wonderful free kick in the last second of the game (2-2). It will be another big fight this time around but it's mostly pride at sake on Sunday.
PSG could be defeated in Marseille on Sunday and miss out on the three points, but they would still easily win the league in May, if not sooner. Yet, weirdly, this is the one game they don't want to lose domestically. They want an 11th league win in a row in as many games this season, which would equal the record set by Tottenham in 1960-1961 for most consecutive top-flight victories at the start of a season in the top five European leagues. They also have an incredible unbeaten run against their archrivals to keep alive: Paris have not lost against Marseille for seven years now, a streak of 17 games and counting.
After the tactical battle against Napoli in which Tuchel and his players will have to use their brains and be at their best to win, Sunday will bring a physical contest against Marseille, for which the German will have to find the right way to prepare his players for the aggression of their opponents.
On Sunday night, we will know a bit more about Thomas Tuchel and his ability to take his PSG team to the top. It is a week of truth and one that should be telling, either for better or for worse.