The 65-year-old was relieved to come through the first game with three points after falling a goal behind last Thursday.
The host nation fell 1-0 down to Marcelo's own goal in the first half against Coatia, before two goals from Neymar and a late Oscar strike secured a 3-1 comeback win.
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The result means Scolari is still unbeaten as Brazil boss at the World Cup, having guided the country to glory back in 2002.
However, the 65-year-old is refusing to rest on his laurels ahead of the clash with the CONCACAF nation, after recognizing the difficulty of the task ahead.
"We mustn't concede first," he told Times of India. "The best thing about football is that you cannot control and pick and choose what favors you. There will be factors that you can't control.
"So, it's better to concentrate on those factors which are in your hand rather than those which are not. Mexico regularly feature in the final rounds. So, they have a rich history which can boost their confidence."
Scolari was also quizzed over the penalty awarded to his side when Fred was adjudged to have been brought down in the penalty area.
Croatia boss Niko Kovac hit out at the decision - which appeared a harsh one on his side - after the game, but the Brazil boss thought otherwise.
"The referee gave his decision and that’s it. We have to accept every decision from the referee and for me, it was a legitimate penalty. So, I had no questions."