A lot can still happen in Japan's pool. A win by Japan over Scotland on Sunday would see Japan top the pool. Scotland need to be Russia on Wednesday with a bonus point and then beat Japan. However, if Japan lost to Scotland while gaining two bonus points, they will still top the group.
Ireland are also in the mix. They need to beat Samoa and hope that Scotland beat Japan to claim top place in the group.
Asked about the prospect of having to play Japan All Blacks coach Steve Hansen said: " I haven't thought about them playing the All Blacks because I think that would be remiss of me to be looking too far ahead and that's not how we operate. We just look one game at a time."
However, he did say, "Japan are playing very, very good rugby. They're exciting to watch, their crowd is right behind them.
"But we could possibly play them, or Ireland or Scotland, all three are still alive but once we find that out we'll have a good look at them.
"It would be a heck of a game from a crowd point of view because all those great Japanese supporters who get behind us probably might flip over and put on a red and white jersey. It would be good if they were on the other side of the draw from that point of view," he said.
The Japan Times described the prospect of the two sides meeting as 'a national showstopper'.
Hansen said: "We look forward to playing whoever it is because that means we're in the quarterfinal and you can't win this tournament if you're not in it.
"But I am really enjoying the fact Japan are having a great tournament because it is great for rugby in this country and one of the side products of this tournament outside of finding a world champion is to promote the game and the more we can promote it the more people will play it.
"The game is bigger than all of us and we want people playing it and enjoying it and having fun doing it so long may they play well," he said.
One All Black who hadn't been surprised that the Japanese side was doing well was fullback Ben Smith who had been coached by Japan's New Zealand coaches Jamie Joseph and Tony Brown when they were Highlanders coaches in Super Rugby.
"They [Japan] are well coached and they are getting them out there to play some good rugby," Smith said.
Centre Jack Goodhue said he had been impressed with Japan's defence.
"Japan is really going out there and their defence is dominating teams. Their technique is awesome and they are putting a lot of pressure on other teams. They are real threats for this World Cup," he said.
Prop Angus Ta'avao said, "They have really set a standard for Japanese rugby, they have been building for a few years and with their inclusion in Super Rugby they have been able to put themselves to the test against high-quality rugby for a long time.
"If we come up against them, we know it will be a tough challenge," he said.