After Japan had efficiently despatched debutants Chile on Sunday, they at once started to worry about what would happen in seven days, while the losers began dreaming about future Rugby World Cups.
Chile struck at the start of each half to force Japan to fight back before winning 42-12.
Next week, the Brave Blossoms face England in Nice after Steve Borthwick's side ambushed Argentina 27-10 late on Saturday.
"It's been a good win for us but we know that it's a different prospect for us," said Japan coach Jamie Joseph.
"Next week we are playing a tier one team, one of the best nations of rugby.
"We saw them dismantle Argentina.
"Physically, intelligently and they play a different kind of rugby. We don't play that way. We can't win if we play that way against England."
Joseph quickly focussed on one area he wanted to improve.
"We did miss a lot of tackles. We have to up the standards. The solution is some tackle training. Get the bags out," he said.
"We aren't as big as the other teams and we have to be accurate with our technique otherwise this is what happens We keep missing tackles we are going to come second."
Japan's points on Sunday came from six converted tries. All England's points against the Pumas came from the boot of fly-half George Ford.
Yutaka Nagare, the Japan captain, said his team would have to adapt.
"Sometimes we will have to pay differently depending on the opponents," the scrum half said.
"We just want to win. The way we win is not important."
Amato Fakatava, named player of the match after scoring two tries, was more worried about the forward battle.
"A lot of things to fix for next week. England are going to be coming strong but we will be ready for that," the lock said before listing: "our line-out and scrum."
Japan started their World Cup without captain Kazuki Himeno who was nursing a calf injury.
Joseph said he wanted to safeguard the back-row forward for tougher tests ahead.
"He probably could have played today but we've come through today's Test match and we look forward to welcoming him back," said the coach.
Joseph was happy to cast Japan in their familiar role as underdogs against England.
"We will have an enjoyable week this week because you guys won't be expecting that we can do anything," he said.
- 'I will never forget' -
Martin Sigren, Los Condoers' captain, was looking past next Saturday's opponents Samoa to future World Cups.
"This is a responsibility on us when we step on the pitch," he said.
"We want to make rugby popular because Chile is a football country at the moment. This World Cup may help, we don't want this to be the only one.
"It wasn't easy to qualify. We want this to happen in the future."
"It's amazing to see your family in the stand. It's difficult to describe it but I will never forget."
Sigren also looked for positives in things that did not go well.
"The last 20 minutes shows what we've always said: that Chile need more matches."
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