When a report first emerged of an incident occurring at a hotel where Mbappe was staying last week, the France international was quick to take to social media to label the news as "fake".
However, on Tuesday, it was reported by local media in Sweden that it was the 25-year-old who was at the centre of the investigation.
As per the report, Mbappe is 'deemed to be a reasonable suspect' of rape and sexual molestation after police were contacted two days after an incident that is said to have taken place on Thursday.
Mbappe was pictured in Stockholm on the Friday, attending restaurant Chez Jolie and the nightclub V on what was a visit to see friends.
His entourage has heavily condemned the accusations, stating that they are "completely false and their dissemination is unacceptable."
How have Real Madrid reacted?
Prosecutor Marina Chirakova has only declared that "a crime was reported on October 10 in central Stockholm" when asked about the case by local media.
Nevertheless, according to journalist Romain Molina, who was commenting on X, Real Madrid officials held 'a crisis meeting' on Monday night.
Mbappe is regarded as one of the world's best players and signed a lucrative contract in the summer when committing his future to Los Blancos until 2029.
He has contributed seven goals and one assist from his first 11 appearances for Real in all competitions.
Despite now playing in Spain, Mbappe will be involved in legal proceedings against former club Paris Saint-Germain on Tuesday as he bids to recoup a total of £46m in unpaid bonuses.
What next?
Much will depend on how the case against Mbappe proceeds at a time when he is also looking to fully recover from the thigh injury that kept him out of international duty with France over the past week.
Real's next three fixtures are against Celta Vigo, Borussia Dortmund and Barcelona, the latter representing Real's most important game of the season thus far as they bid to close down a three-point gap to the La Liga leaders.