Belgium overcame a 2-0 deficit to beat Japan 3-2 in their round of 16 game in Rostov-on-Don on Tuesday morning.

"When you play against Brazil, you need to understand that they are the best team in the competition. You have to accept that," said Martinez.

"The quicker you understand your role, the better, as everything gets clear.

"So against Brazil, we will have to have a real clarity of how to play such position and a quality of such players as Coutinho and Neymar, who can decide the game in one second. I don't think we are favourites in the game against Brazil, but we will enjoy it from the first minute," he added.

He added that it is many players' dream to play at the World Cup and play against Brazil.

The match takes place in Kazan on Saturday morning (AEST).