Scolari blasted his side after a Sunday training session which he said he "didn't like at all" owing to poor marking and perceived sloppiness.
And with only ten days to go to their opening World Cup match against Croatia in Sao Paulo, the man who led the Selecao to glory in 2002 insisted it was time to crack the whip.
Sunday, "the marking was sloppy, we left spaces in the middle of the park and took up questionable positions," Scolari observed.
Tuesday's test at the Serra Dourada stadium in Goiania, some 200 km (130 mi) from the capital Brasilia, is the penultimate chance for Scolari to look at options in reserve.
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Friday against Serbia in Sao Paulo is his side's final friendly outing before the real thing starts with the Croatians in a Group A also comprising Mexico and Cameroon.
Scolari, calling for more inventive subtlety and tactical nous from his charges, said the players know full well what he demands and expects.
Scolari can make up to six substitutions in the game against the Panamanians and said he would use the chance to run the rule over the options at his disposal.
Even so, against Croatia he will essentally keep faith with the players who saw off Spain in the Confederations final.
Scolari, who said he would have liked a few more days to prepare for the June 12 opener at Sao Paulo's Corinthians Arena, said Panama were not to be underestimated.