OPINION: What a difference a few days can make in the sporting world…
Only last Friday, we were lauding Ireland's rise up the Newshub Rugby World Cup power rankings with their comprehensive opening victory over Scotland.
Four days later, they're again big movers - but downwards this time, after their stunning defeat by Japan on Saturday.
- 'Sub-conscious bias' plagues Polynesian players at World Cup
- Watch: Japan upset throws All Blacks quarter-final wide open
- Five greatest upsets in Rugby World Cup history
Despite that result, it's probably a little too early to boost the home side into the top echelon just yet. Remember, they toppled South Africa at the last tournament and still could get out of pool play.
But that outcome has certainly captured the imagination of rugby fans in the host nation and makes Pool A must-see TV over the next two weeks.
Here's how we see the World Cup's top 10 on current form…
Last week: First (-)
This week: No game
Unlike many around them, the All Blacks haven't done anything to fall from their top rank and emerge from a 10-day break with fixtures against the tournament two weakest teams.
They'll need to come out firing against Canada to maintain the early-tournament momentum established with victory over South Africa.
Next game: v Canada, October 2
2. South Africa
Last week: Third (+1)
This week: Beat Namibia 57-3
Probably should have managed more against a team that would struggle to survive in their domestic competition. A steady-as-she goes result, but they will want their top team to put on an improved showing next up against the pool's potential spoilers.
Next game: v Italy, October 4
Last week: Fifth (+2)
This week: Beat Australia 29-25
Barring upsets, the Welsh virtually sealed top spot in Pool D with their controversial win over the Wallabies, who have taken the result with their usual diplomacy.
Now they have a loooong break, which could potentially stall their momentum, with a couple of tricky opponents still to come.
Next game: v Fiji, October 9
Last week: Fourth (+1)
This week: No game
Idle since their big win over the United States last Thursday, after facing the easiest opening draw of our top contenders, the English will need to show something more than they have against the dangerous Pumas in their next outing.
Next week: v Argentina, October 5
Last week: Second (-3)
This week: Lost to Japan 19-12
No team has ever won the Rugby World Cup, after losing in pool play. Can Ireland be the first?
An opening win over Scotland still gives them inside running on a quarter-final spot, but unless there's a further twist to Pool A, their opponents there could be the two-time defending champions.
Next game: v Russia, October 3
Last week: Seventh (+1)
This week: Lost to Wales: 29-25
No dishonour in this defeat, but maybe in the bleating afterwards. Blamed their result on the only participants who couldn't defend themselves, instead of their own shortcomings, but that's Cheika's seige mentality at its glorious best.
Uruguay's win over Fiji - and then loss to Georgia - may have eliminated the biggest threats to Pool D's top dogs, but the Wallabies should still be nervous of another South American upset.
Next game: v Uruguay, October 5
Last week: 10th (+2)
This week: Beat Ireland 19-12
Fantastic result to topple the recent world No.1 team and really throw Pool A into disarray, but they'll need to ride that wave of euphoria to its very end to seal their first knockout appearance at a World Cup.
When they beat the Springboks four years ago, they lost to the US and could not progress. They still have two games that could very easily trip them up.
Next game: v Samoa, October 5
Last week: Sixth (-1)
This week: No game
Another team idle over the weekend, everyone will be intrigued to see which version of the French emerges from the 10-day lay-off, since a schizophrenic opening over Argentina.
Two relatively easy outings loom, although they'll be wary of the Tongans, who beat them in 2011 pool play.
Next game: v United States, October 2
Last week: Eighth (-1)
This week: Beat Tonga 28-12
Weren't overly impressive against the Pacific Islanders, after showing glimpses of their ability in an opening loss to France.
Hopefully, they're saving their best for a tilt at upsetting England to throw this pool wide out too.
Next game: v England, October 5
Last week: Ninth (-1)
This week: Beat Samoa 34-0
More than a week after their spineless opening loss to Ireland, they did the business over the Pacific Islanders, but slip another notch to Japan's shock result over the Irish.
Hopefully, they're back on track and if they can beat the home team, that pool may still come down to a messy three-way countback or bonus points, so a big win over their next opponents is crucial.
Next game: v Russia, October 9
Grant Chapman is Newshub online sports editor.