The South Americans secured a point from their opening game against Italy with a late goal from Amanda and Okon has told his girls to be careful.
'You saw how they came back in the dying minutes of the match to score their equalizer. It shows that they are a team that you should not dismiss so easily.
Yes, Italy had a player sent off, but we have to be careful," Okon preached at Tuesday's training session.
"This is a tournament that a game can change in five minutes that is why my players must know the importance of being focused till the last minute," he added.
Defender, Josephine Chukwunonye and Striker, Desire Oparanozie who were slightly tackled by their opponents have been declared fit by the team medical personnel for today's match.
This will be the third meeting between Brazil and Nigeria and sixth appearance in this competition.
At the 2004 edition in Thailand Nigeria defeated Brazil 3-2 in the group stage and two years later in Russia, the South American got their pound of flesh winning 3-2 in the quarter final.
The late Felix Ibeh, who handled the team in Thailand, was also the head coach of domestic side, Rivers Angels that Okon now coaches.
The game on Wednesday is at 7am Nigeria time and will be live on SuperSport.