Kaka: 50 percent chance of facing Ecuador
Team doctor Jose Luis Runco said that the AC Milan player had undergone an examination on his injured foot and that no damage to the bone had been found.
"He was feeling a bit of pain in his foot and we chose to do an exam," Runco told reporters. "Now, we're going to try and work to get him in shape for the two games.
"He wouldn't be able to play today but we haven't started the treatment yet. We've got a 50 percent chance."
Brazil, second in the South American World Cup qualifying group but six points adrift of leaders Paraguay, face Ecuador at high altitude in Quito. Three days later, they host Peru in Porto Alegre.
Brazil coach Dunga said he was including Kaka in his plans.
"We're taking the optimistic view that he can play," Dunga told reporters. "We have 22 players, he's important but we have to wait to see how the treatment goes."
"He won't be 100 percent, obviously, but he can certainly participate."
Inter Milan striker Adriano is also doubtful because of an ankle injury and missed training on Tuesday.