Rugby World Cup: Upsets are gold ... but can't last

Japan’s shock result good for game, however big guns will reach quarters

In the wake of Japan's astonishing victory against the Springboks it may feel like rugby has slipped from its axis and just about anything is possible at this tournament.

As much as the unexpected has created new scenarios no one ever thought would require contemplation, reality may well be restored by the knockout rounds.

Rugby romantics - and right now who isn't - can cling to the dream of the impossible repeating. Japan and Samoa in the last eight? Fiji surging past Australia to throw Pool A into unfathomable connotations? Georgia toppling Argentina? Everyone's started believing some or all of this is possible and every pre-tournament prediction is being revisited.

But hold the phone. This can't last. It won't last. It has been a brilliant opening - the most dramatic in history.

It's just one weekend, though. South Africa will feel like they have fallen off a cliff, which they kind of have. But not from a fatal height and as long as they regroup and cast out the mental demons, they can scramble their way back up. Probably as pool winners but certainly as runners-up.

"It would be very foolish for anyone to think they can rock up and take South Africa lightly now because Japan has beaten them," was All Blacks coach Steve Hansen's assessment.

"It is irrelevant what happens game to game. If you have got talent and the ability to improve then it is a different beast you are going to get the next time you play."

The Boks are too good not to bounce back and it would be an enormous and indeed reckless bet to say they won't still make the last eight.

History shows that pool-round humiliation is no bad thing: England suffered it in 2007 - losing to the Boks 36-0 and still made the final. France lost to Tonga last time around and still made the final.

South Africa can recover, most likely will and by the time there are eight teams left, this World Cup may still have an entirely familiar look.

While Japan are going to be everyone's favourite "other" team and willed on by millions of neutrals, it's a leap to imagine they can push on from here to make the quarter-finals.

Their brand of rugby is compelling. They are well-drilled, highly skilled, composed and brave. They will be tough to beat, yet still beatable and Scotland and Samoa will both feel, despite what happened in Brighton, that they start as favourites.

Japan, after all, can't defy physics for ever and their lack of size and presence will bite at some stage.

If there is to be a surprise package at this tournament it may well be the Pumas. A sensible and solid pick to make the quarter-finals, few have backed them to go further. On the strength of their performance against the All Blacks, that should be reconsidered.

They are likely to face either Ireland or France - sides against whom they have enjoyed recent success, most notably beating both, the latter twice, at the 2007 World Cup.

"I think it has been a great weekend for World Rugby because they are the keepers of the game and they want more than seven or eight teams in the world to be competitive," said Hansen. "They want a World Cup where everyone can come and look to be successful. I think Japan have opened the eyes of the rugby world. People who are watching for the first time will be thinking 'wow, here is one of the wee guys doing a great job'."