ROSTOV-ON-DON, Russia -- Monday's game kicked off at 3 a.m. Tokyo time. An unsociable hour, so provisions were made, specifically by Tokoji Temple in Shizuoka, which opened its doors to allow local fans to watch their Japan side play Belgium in an atmosphere of zen Buddhist calm. One hopes a few of them took up the offer, because it might be the only way of reconciling how Japan managed to lose.

Belgium will need no such cerebral soothing. Through by the skin of their teeth, a team featuring Romelu Lukaku, Kevin De Bruyne and Eden Hazard were saved with the last kick of the game by West Brom's Nacer Chadli to reach the quarterfinals of the World Cup with a 3-2 win.

Roberto Martinez has always been a faintly unconvincing manager, a man who talks a good game but managing one ... sometimes not quite so good. Usually, one would instinctively praise a manager who brought on two substitutes, both of whom scored as their team came from 2-0 down to win, but with Martinez there's at least cause to pause.

There are always two schools of thought when it comes to stuff like this: Do you judge the result or the process? Do you simply say Martinez brought on Chadli and Marouane Fellaini, who both scored, ergo they were the right decisions, a plan executed perfectly? Or do you think he got lucky with a move of desperation, a Hail Mary that somehow landed?

Belgium, needless to say, will not care Monday night. Or Tuesday. But on Friday, when they face Brazil in the World Cup's last eight, they might have to. "In the World Cup you want to be perfect, but it's about getting through, it's about winning," Martinez said afterward.

The question that instinctively occurs, after Chadli's late intervention beat a Japan side that throughout the tournament had been much more robust than we'd been led to believe, is does this victory say good or bad things about Belgium's prospects against Brazil?

World Cup 2018 must-reads

- Make your daily picks with ESPN FC Match Predictor 2018!

- World Cup fixtures, results and coverage

- World Cup Daily live: Join ESPN for all the action

- Spain's World Cup failure down to Lopetegui's shock sacking

- Neymar: A selfish brat or misunderstood genius?

- Argentina at a crossroads as post-Messi era looms

Does the fact that they required a goal with 8 seconds to go, following a moment of staggering naivety from Japan when they crossed a corner rather than taking it short, mean there are deficiencies in this team that Neymar, Philippe Coutinho and pals will leap on and tear apart like coyotes on a leg of lamb?

Belgium players celebrate at full-time of their World Cup win against Japan on Monday. Getty Images

Or does the late winner prove that this is a side of fortitude, of substance, who firstly will not give up but also, most important, have an effective Plan B? Does it indicate that they are clear of thought in moments of intense pressure, evidenced by Lukaku's frankly audacious dummy, allowing the ball to run through for Chadli to score at the last?

The truth probably leans more toward the former, but they will believe the latter: So which is more important? Belgium will, perhaps, not forget that they were 2-0 down to Japan, but certainly remember more that they came back to win 3-2. You might call that a sort of delusion, but sometimes footballers need to delude themselves. If every striker thought about the possibility of missing a chance before putting it away, they'd never score another goal again.

"To win was important for our confidence," Chadli said afterward, to illustrate the point. "To lose today ... you can lose a game, but the way we've been playing, we can't lose like this. We had to change something, change the mentality and we fought for each other. And that's what got us the win."

It will be Martinez's job to address the weaknesses, to ensure they don't make similar mistakes in their quarterfinal. Belgium seemed to approach this game in a similar manner to their defeat in Euro 2016 against Wales: They expected to win, and in the opening exchanges they played like a side who just sort of assumed a goal would go in at some point. Like they would be rewarded by some karmic force, because they were playing well, and that's how things work.

They won't do that against Brazil, of course. Indeed, their mentality will be flipped entirely. For the first time in Martinez's reign, Belgium will be underdogs in a competitive match. If you ignore the England game -- a glorified "B" international in which neither team was crazy about winning -- then their toughest test under the Spaniard was against Bosnia-Herzegovina. A good team, but no Brazil. It will be fascinating to see how they adapt.

There were enough signs against Japan to concern them going into Friday's game. If Takashi Inui, a right-footer coming in from the left, can cause them that many problems, then what will Neymar do? Will Jan Vertonghen make another mistake like the one that led to Genki Haraguchi's opener?

This was Belgium's toughest test under Martinez so far, a Japan side who pushed them to the very edge. They only just passed, and now they have plenty to think about before an even tougher examination this weekend.