Just two days before their debut in the competition against Egypt, the Selecao will have to do without the 22-year-old who has been forced out with an elbow injury
The highly-rated shot-stopper, 22, was expected to be the Selecao's first choice throughout their campaign in Great Britain.
However, he suffered a serious knock to his right elbow during Monday's training session, however, and was immediately identified as a doubt for the tournament.
On further examination, Brazil doctor Jose Luis Runco confirmed that Rafael would not be playing any part in the Olympics.
"He suffered elbow trauma and, after examining him, he was in pain and had very little mobility," the medic explained to reporters.
For the position he plays in and because of the Olympic rules, we only have 18 players and two goalkeepers, we did not have another choice.
"He needs rest and, as we have only two [goalkeepers] we had to take the time to sit down and talk with the coaching staff about the need to swap players."
Although national team director Andres Sanchez refused to confirm the name of Rafael's replacement, Atletico Mineiro keeper Renan Ribeiro is expected to get the call and, according to Globoesporte, will arrive in London on Tuesday evening.
Brazil make their Olympic bow on Thursday, when they face Egypt in Cardiff's Millennium Stadium.