Lionel Messi was back in the team for the first time since the Copa America after serving a four-match ban for accusing CONMEBOL of corruption.
He scored the decisive goal early on when pouncing on the rebound after seeing Alisson save his penalty a few moments after Gabriel Jesus had also failed to convert from 12 yards.
Otherwise it was a scrappy and disjointed affair, though Argentina looked considerably more threatening in the final third and were unfortunate to not add to the score in the second half.
Despite Argentina's wastefulness after the interval, Scaloni was left overjoyed with the mentality and attitude of his team.
"I liked the second half," Scaloni told reporters. "We made changes because we wanted to test for what is to come.
"The team responded – it goes beyond who plays. They give their lives for the shirt and really played well."
Argentina remain unbeaten in their five post-Copa America matches, while Brazil – who have also played five times since lifting the trophy – are winless in that period.