"I believe that he won't miss out because, with this type of problem, the tendency is that he will recover in time," team doctor Jose Luis Runco told reporters on Tuesday. "It's nothing serious."
Ronaldo missed Real Madrid's Spanish Primera Liga defeat by Deportivo Coruna on Sunday and stayed in the exercise room on Tuesday while the rest of the Brazil squad trained.
Coach Carlos Alberto Parreira said he would decide on Ronaldo after a practice game on Thursday.
"I'll wait until the (Thursday)
The world champions, who lead the 10-nation South American World Cup qualifying group with 16 points from eight games, are away to Venezuela in the steamy oil city of Maracaibo before facing Colombia at home four days later.
Ronaldo is top scorer in the tournament with seven goals.
Runco said that midfielder Juninho Pernambucano, who took a knock on the calf while playing for his French club Olympique Lyon at the weekend, should also be fit for Saturday.