Dani Alves was arrested on Friday by police in Barcelona after it was alleged he sexually assaulted a woman in a nightclub bathroom.
The former Barcelona right-back gave a statement to the Mossos d'Esquadra police force before the public prosecutor's office requested that he should be detained and not granted bail.
Spanish news agency EFE reported how that application, plus a private prosecution brought by the woman who made the allegation, would be put to the investigating judge to determine whether Alves is kept in prison while investigations continue.
Alves, 39, has also played for Paris Saint-Germain and Sevilla, and returned for a second spell at Barcelona last season, before joining Mexican team Pumas UNAM.
The incident under investigation is alleged to have happened on the evening of December 30.
In a video sent to Spanish broadcaster Antena 3 earlier this month, Alves denied assaulting the woman.