Former Brazilian footballer Ronaldinho and his brother appeared in court on Saturday over allegations the pair used fake passports to enter Paraguay.
Prosecutors say the brothers were given the false documents when they landed in the capital Asuncion on Wednesday.
The pair were taken into custody on Friday, just hours after a judge refused to uphold a prosecutor's proposal for an alternative punishment.
The prosecutor argued the brothers had been tricked. They deny any wrongdoing.
The pair, who were questioned by police, said they thought the passports were a courtesy gesture. Officers later searched their hotel.
At the court in Asuncion on Saturday, a judge ordered that Ronaldinho and his brother, Roberto Assis, be placed in pre-trial detention.
In July 2019, the player reportedly had his Brazilian and Spanish passports confiscated over unpaid taxes and non-payment of fines for illegally building on a nature reserve in Brazil.
"I respect his sporting popularity but the law must also be respected. No matter who you are, the law still applies", Paraguay's Interior Minister Euclides Acevedo told local media this week.
The 39-year-old had travelled to Paraguay to promote a book and a campaign for underprivileged children.
Ronaldinho was the 2004 and 2005 World Player of the Year and reached the prime of his career at Spanish giants Barcelona. He won the World Cup for Brazil in 2002 alongside fellow superstar forwards Ronaldo and Rivaldo.
Ronaldinho's net worth is estimated at £80-100m and he is reported to charge around £150,000 for a single promoted Instagram post.