A Brazilian police document says an unidentified woman has accused Neymar of raping her in Paris last month. The player's father calls the incident "a setup" against his son.
The document obtained by The Associated Press on Saturday says the incident took place on May 15 at 8:20 pm local time in a hotel.
The woman went to police on Friday in Sao Paulo.
Neymar's representatives have not replied to a request for comment, but his father and agent Neymar dos Santos denied any wrongdoing by the player in a television interview.
"This is a tough moment. If we can't show the truth quickly it will be a snowball.
If we have to show Neymar's WhatsApp messages and the conversations with this lady, we will," Neymar dos Santos told TV Band.
The woman says she and the Brazil star met in France after exchanging Instagram messages.
She told police a representative of the Paris Saint-Germain player named Gallo allegedly bought her tickets to Paris and booked her a hotel room. She said Neymar arrived apparently drunk at the hotel.
The woman described to police that they "touched each other, but in a given moment Neymar became aggressive and, with violence, had sexual intercourse against the victim's will."
The text also says the woman left Paris two days later and said she did not file her complaint in Paris because she was shaken.
The police document says the woman will go through medical exams as part of an investigation.
Neymar is in Brazil preparing for the Copa America starting next week.