The former Ballon d'Or winner was reported to be taking part in a five-a-side prison tournament, in order to bring inmates together to compete for a bizarre prize of a 16kg suckling pig.
Pictures appeared of Ronaldinho featuring in the action, wearing a white vest and a pair of floral shorts along with AstroTurf trainers.
Sporting his trademark ponytail, the Brazil icon looked to be straight in among the action as the tournament got underway upon a small concrete pitch.
A later image the showed Ronaldinho surrounded by team-mates, clutching a golden trophy.
The team boasting the former Barcelona and AC Milan superstar won the final match 11-2, with Ronaldinho scoring five goals and assisting in the remaining six.
The 39-year-old was detained after being arrested for allegedly attempting to enter the South American country of Paraguay with a fake passport alongside his brother.