The most experienced player in the current Selecao injured his right knee against Mexico and will sit out Tuesday's training session, with Bruno Uvini the favourite to replace himMano Menezes has already begun preparations for Brazil's friendly with bitter rivals Argentina on Saturday, with the coach waiting on a decision regarding the fitness of Thiago Silva.
The Selecao returned to the training pitch on Tuesday at Rutgers University after being defeated 2-0 by Mexico over the past weekend, their first negative result of 2012.
However, Thiago Silva complained of pain in his right knee during that encounter and will not take part in the first session, according to Globoesporte.
Should the AC Milan centre-back not make Saturday's match in New Jersey, Sao Paulo's Bruno Uvini looks set to play alongside Juan at the back.
The 21-year-old has made two appearances for the senior team and was a member of the Under-20 side that lifted both the South American and World Cup titles in 2011.
Aside from Thiago Silva, Menezes is expected to field an unchanged XI against Argentina, who come to the USA on top form having disposed of Ecuador 4-0 at the weekend.
Santos keeper Rafael will continue in goal, while his Peixe team-mate Neymar will once more form a potent attacking trident alongside Internacional's Leandro Damiao and Hulk of Porto.
Possible Brazil XI against Argentina (4-3-3): Rafael; Danilo, Thiago Silva or Bruno Uvini, Juan, Marcelo; Sandro, Romulo, Oscar; Hulk, Leandro Damiao, Neymar.