Although Live Nation have yet to officially announce tour dates in Brazil, the official site of the Rio de Janeiro Maracanã Stadium is stating that there are two dates booked for an 'International Show' on Saturday 13 December and Sunday 14 December.
Fans can see online at www.suderj.rj.gov.br/cultural (at the bottom of the page on 'Dezembro')- however fans should remember this is just speculation at this moment and nothing is official until announced by Madonna.com/Live Nation.

Source: Madonnalicious