Japan's Rugby World Cup quarterfinal against South Africa on Sunday could well end up being determined by which coach is the better poker player.

At first glance, it would appear Springboks coach Rassie Erasmus has made his intentions very clear by packing his bench with six forwards.

The Brave Blossoms, on the other hand, has progressed to the last eight for the first time with a game that has stunned their opponents and overseas fans alike, thanks to their ability to execute their skills at an incredible pace.

There are suggestions though, from those that follow the Springboks regularly, that Erasmus could spring a surprise and get his team to ship the ball wide to make use of wings Cheslin Kolbe and Makazole Mapimpi.

And Japan coach Jamie Joseph signed off his pre-match comments with a teaser that hinted perhaps the Brave Blossoms will do something different.

On Saturday, his longtime assistant coach, Tony Brown, however, was following the party line.

"There's only one thing they are going to do and that is intimidate us," Brown said at the team's hotel.

"It's their game, it's based on forward dominance and they are good at it. Our challenge is to play our game and entice them into playing Japanese rugby."

A style of rugby which South Africa assistant coach Mzwandile Stick said was similar to the French rugby of the 1970s.

"The Japan side play with a high tempo," he said Friday evening at Tokyo Stadium.

"They have got very skillful players, and they are well-drilled when it comes to coaching. When you look at the way they play, we call it champagne rugby, where they put it through the hands and punish you.

"We need to make sure we are switched on, and are well-organized, because they are going to pick up the tempo."

The game naturally has people bringing up "The Brighton Miracle" — Japan's shock win at the World Cup four years ago — and its more recent encounter in September in Kumagaya, Saitama Prefecture, won 41-7 by the Springboks.

The two sides, however, say the past has no bearing on Sunday's game.

"Both teams had different things on their mind," Brown said of the more recent game. "We played a style of rugby that was planning around the World Cup, not around South Africa. It has no reflection on what happens tomorrow."

South Africa captain Siya Kolisi was involved in both games — the only two times the nations have faced each other in a test match.

"That was very tough to lose that match in England," he said. "That stuck with us until that game when we got here (in September). It's something that we never want to go through again."

"Now it's a different game again. We are going to have to be at our best again, because they have really improved as a team — they are much better now than four years ago. So, we are looking forward to the challenge."

South Africa lost its opening pool game against New Zealand but then had the luxury of playing teams much lower in the world rankings.

Japan, meanwhile, went through the pool stage unbeaten, knocking off two Tier 1 sides in the process.

The big question is who is best prepared for a one-off knockout game.

"Luckily for us, it's been do-or-die since the first game, so we've been in that mindset for a couple of weeks now," said Kolisi.

"It's not like any other test match. It's playoff time now. We have all prepared for it mentally ... we know what needs to be done. I don't think anybody needs to tell us that this is a big game. If we don't know that already, then we are in the wrong place."

Despite the weight of being the host nation on their shoulders, the Brave Blossoms have spent this week treating this game as any other.

"It's all about being consistent, building details and focusing on what is in front of us," said scrumhalf Yutaka Nagare.

The game has so many great matchups, none more so than in the back row and on the wings.

Kolisi, Pieter-Steph Du Toit and Duane Vermeulen up against Michael Leitch, Pieter Labuschagne and Kazuki Himeno is set to be an epic battle of physicality.

Kolbe and Mapimpi taking on Kotaro Matsushima and Kenki Fukuoka sees four of the most exciting runners and finishers in world rugby go head-to-head.

It could well boil down to which kicker is on form.

"It's playoff rugby," Springboks flyhalf Handre Pollard said. "We all know the history of penalties in World Cups, so it's no secret — it's very important and could play a massive role in this match."

His opposite number, Yu Tamura, did not have a game to remember back in September. But he has got better the longer tournament has gone and comes into the game as the top points scorer with 48.

It's a match Japan has never witnessed before.

As Brown said, "It's a one-off quarterfinal. The winner goes on and the loser bows out. It's what the game is all about."