A French Cup trip to bitter rivals Marseille on Wednesday is the start of seven days that could define this season for Paris Saint-Germain, with a Champions League showdown against Bayern Munich approaching.
The Bundesliga giants visit the French capital for the first leg of their Champions League last-16 tie next Tuesday, but there will be no easy build-up to that game for PSG.
Marseille await them in the bear pit of the Velodrome for a French Cup last-16 tie as the Parisians aim to reclaim a trophy they missed out on last season after winning it six times in the previous seven years.
Then they go to in-form Monaco on Saturday. A match that could be one of the biggest obstacles remaining to their title bid in Ligue 1. They are eight points clear of nearest rivals Marseille and Lens at the top of the table.
PSG have an excellent Cup record against Marseille, winning 10 of the 11 past encounters between the clubs, including two finals in the last two decades.
Yet while Marseille will have a hostile crowd in their favour with 65,000 fans behind them on Wednesday, PSG's domestic superiority has been questioned in recent weeks.
Christophe Galtier's team won just one of their first four league matches in 2023 before getting the better of Montpellier and Toulouse in recent days.
They needed a fine Lionel Messi strike to win 2-1 against the latter on Saturday after losing Kylian Mbappe to a thigh injury that will keep him out of the Bayern first leg too.
Mbappe has risen above Messi and Neymar to become comfortably PSG's most important player. His absence at such a key stage of the season is a hammer blow.
Marco Verratti's return from suspension will at least provide a huge boost in midfield, but PSG's defence has also appeared vulnerable of late and a Marseille attack led by Alexis Sanchez could exploit their weaknesses.
- 'Play for Leo' -
Neymar is back in training after a minor muscle injury but Galtier is in no doubt that, without Mbappe, the main man is Messi.
"I ask the team to play for Leo and to do the work for him," the coach said.
"We need to free him up from doing certain tasks. His teammates are going to have to put in twice as much effort when it comes to winning the ball back and in terms of movement so he can play the kind of passes in tight spaces that are so rare in football these days."
Marseille, who also host PSG in the league later this month, had gone 10 games unbeaten before losing 3-1 at home to Nice on Sunday.
It was a disappointing night for Igor Tudor's team, with Vitinha, the Portuguese striker signed from Braga for 32 million euros ($34.3m) before the January transfer deadline, substituted at half-time on his debut.
"We have done some really good things since the start of the season so the fact we have lost one game does not mean we will be short of confidence on Wednesday, on the contrary," insisted Marseille midfielder Matteo Guendouzi.
Elsewhere in the last 16, Laurent Blanc's Lyon, enduring a difficult season in the league, take on Lille, while holders Nantes are at Ligue 1's bottom side Angers and Lens go to Lorient.
French Cup last-16 ties
Wednesday (1715 GMT unless stated)
Angers v Nantes, Auxerre v Rodez, Lyon v Lille, Paris FC v Annecy, Toulouse v Reims, Vierzon v Grenoble, Marseille v Paris Saint-Germain (2010)
Lorient v Lens (2000)