When everything seemed like it was going to be a tribute on his magnificent season, Mbappe decided it was the right moment to open Pandora's box.
The PSG striker, the rising star of world football, did not hesitate to say some words, which, as soon as they left his mouth, became an absolute bombshell.
"I have discovered many things in my team, maybe it is the moment to take on more responsability. I hope it is at PSG, which would be beautiful or maybe in elsewhere in a new proyect," said the Frenchman.
A simple phrase which has left wide open the door to a possible exit from the Parisian club. Or maybe he wants to become more important next season...
And the thing is the French international's message could be interpreted in many different ways, all of them very sensible interpretations.
Time to leave?
The first of them is, without doubt, that opening to a future departure from PSG, whether it is this summer or maybe in 2020.
That 'or maybe in another place" could clearly mean that Mbappe is now thinking about the next step in his career which Ligue 1 cannot offer him.
The competittion seems too small for the current number '7' for PSG and a challenge like one in La Liga would be much more appetising, especially taking into account that a team like Real Madrid and their coach Zinedine Zidane would welcome him with open arms.
The attack was close to moving to the Bernabeu in summer 2017 and maybe with these words he is preparing for a future away from Paris.
Is he putting pressure to get a pay rise?
What Kylian said on Sunday night, as well as being a possible desire to leave, could also be understood as a way of putting pressure on his club to improve his contract.
Since in recent years, PSG have had to face the situation of various key players flirting with a move to other big clubs so that the Parisian side review their contracts.
One of the most high profile cases was Verrati's to Barca two summers back. The Italian invited the Catalan club to go for him, but his real desire was to improve his economic conditions.
It's probable that Mbappe looks for the same and wants to be the best paid player of the squad, a privilege which Neymar currently holds, since his value does not stop growing and his performance has been superior to the Brazilian's.
More protagonism... and goodbye to Neymar?
In his appearance, Mbappe made it clear that he wants "to take more responsability." Words which reflect the winning and competitive character of the Frenchman and his bravery to make the demand.
Taking on that responsability could mean the "moving" of the some of PSG's stars which could end up leaving the club.
Cavani's name has been heavily linked with a move away this summer. Maybe Kylian wants to take on the role of a centre forward and that ends up bringing about the departure of the Uruguayan.
It is clear that his speed down the flank makes him a fearful player, but being the main man up front could make his goalscoring figures multiply.
On the other hand, that claim of protagonism could be understood as a message to the PSG board so that they make him number one over Neymar.
The Brazilian left for PSG to be the main man after being in Messi's shadow at Barca and now he could become second to Mbappe.
A situation which could become uncomfortable for the player and the club and could also bring about a possible departure of the number '10'.
A goodbye which, just like in the hypothetical departure of Mbappe, would have the Bernabeu as a possible destination. A massive issue which come to the fore with a simple phrase uttered by Mbappe.