"We faced Japan not long ago in a friendly… I think in essence [the team] is exactly the same, footballers with an incredible, incredible energy… I expect a very tough game, a game that we'll have to be concentrated at all times because they [Japan] are capable of creating problems," Martinez said at the pre-match press conference.
The head coach went on saying that the team was not underestimating their opponent and the match could go all the way to the penalty shootout.
Belgium, who won all three of their group-stage games, are set to face Group H runners-up Japan in their round of 16 match at the Rostov Arena on Monday.
Japan Not Preparing for Penalties
Speaking about the upcoming game, Japan head coach Akira Nishino stated that his side had something to show Belgium.
"We fought bravely in the group and I would like our team to be regarded as equal to Belgium. We did our best at the group stage but I feel and I know that the players still have something to show. We are in perfect shape ahead of tomorrow's match," Nishino told journalists.
As Akira Nishino announced, his side was not preparing specifically for a penalty shootout.
"Of course, I make the decision concerning the penalty shootout, and I need to know the situation in the team… I was appointed to this position [of the head coach] not so long ago. Our team has never prepared for the penalty shootout specifically. I don't think we should practice penalties during our training sessions. We haven't done it," Nishino told journalists.
He explained that the players' mental approach meant a lot during penalties.
"We can't prepare for that [the penalty shootout], as mental approach means much… The main burden lies on the one who strikes, not on the goalkeeper," Nishino added.
The 2018 FIFA World Cup kicked off on June 14 and will continue until July 15, with the matches being played in 11 cities across Russia.