Rugby World Cup 2015: Power Ranking Teams After Week 1

Power is temporary and the opening weekend of the 2015 Rugby World Cup has already seen one of the game's titans tumble down our list, while a less-fancied nation took giant steps in the opposite direction.

Japan are the biggest movers in our power ranking following a stunning win over South Africa on Saturday, while New Zealand, Ireland and England made solid starts to their campaigns.

Not every team has yet been in World Cup action, but our form-based pecking order nonetheless takes each team's recent results and strengths into account to get an idea of who's performing to their optimum at present.

Read on to find out which nations are moving up the order thanks to some promising group-stage displays thus far, while others have tumbled in the opposite direction after failing to hit the ground running.

Don't forget to check out last week's power rankings and see how each team has fared following the opening matches of the 2015 Rugby World Cup.

20. Namibia

Dita Alangkara/Associated Press

Movement: Down One

Anticipation is building up to Namibia's 2015 Rugby World Cup opener against New Zealand on Thursday, with the lowest-ranked team in the tournament poised to take on the world No. 1 and reigning champions.

Opening their tournament late is likely to be a setback in itself for Namibia, but few people will hold out hope for the minnows, despite claiming their second-successive African Cup earlier this year.

19. Romania

Andreea Alexandru/Associated Press

Movement: Down One

Nations Cup champions Romania are also down in our rankings after failing to feature in the first round of matches so far, but take on France on Wednesday looking to cause a shock.

Victory in this year's Nations Cup—Europe's second-tier tournament—has given Romania a boost in confidence, but Canada remain the only Pool D side they appear to have any chance of beating.

18. Canada

Movement: Down One

A 50-7 demolition at the hands of Ireland made Canada the second-heaviest losers of the pool stage's first round, where DTH van der Merwe's fortunate breakaway try was the only excuse for a consolation.

Captain Jamie Cudmore was shown a yellow card and found it tremendously difficult to marshal his troops against one of the competition's strongest forces, with Canada relying too heavily on a select few stars.

17. Uruguay

Alastair Grant/Associated Press

Movement: Up Three

The absence of Romania and Namibia from the early World Cup schedule helps Uruguay's cause in this week's rankings, but the South Americans were very stubborn for periods of the 54-9 loss to Wales on Sunday.

Uruguay may have reflected their amateur status in their performance at times, but they still raised some concern at the Millennium Stadium, particularly after leading the Welsh 10 minutes in.

16. United States

Movement: Down One

On any other day, the United States may have found their opening match against Samoa go in their favour.

As it was, however, the Pacific Island nation came out on top with a 25-16 win in what became a fervently contested Pool B clash.

But Chris Wyles and his United States team-mates were unfortunate not to get at least a losing bonus point from the tie, as they were ultimately beaten by just a few moments of magic from Samoa.

15. Tonga

Movement: Down Three

Just as they did in the official World Rugby rankings following a 17-10 loss to Georgia, Tonga drop down three places this week despite enjoying 83 per cent possession in the second half of the game.

Mamuka Gorgodze's men were a defensive unit to behold at points, but this was more an exposing of Tonga's technical flaws where they made 160 runs to Georgia's 59.

However, the Tongans were still only able to come up with one try, scored by Fetu'u Vainikolo.

14. Italy

Frank Augstein/Associated Press

Movement: None

It's draining to raise the point once more with no way of telling whether the Azzurri would have fared any better with their captain present, but Italy were still lacking the ingenuity of Sergio Parisse en route to a 32-10 defeat against France.

But despite a lack of line-breaking penetration, Jacques Brunel's side did still manage to account for a majority of possession in both halves and make more turnovers (14) than their opponents (10).

13. Scotland

Christophe Ena/Associated Press

Movement: Down Three

It's harsh to punish Scotland so drastically when they have yet to kick a ball at this year's Rugby World Cup, but an unavoidable decision given the improvements of so many sides around their level.

Vern Cotter's men face Japan on Wednesday in what has, arguably, become the biggest fixture of their Pool B campaign. Victory could see them shoot up the standings and challenge for a first-place finish.

12. Georgia

Movement: Up Four

A seven-point victory over Tonga means Georgia have now won a game at their last three World Cups, but Saturday's win at Kingsholm also happens to be their biggest success at the competition to date.

Positive results against Namibia and Romania in 2007 and 2011, respectively, pale in comparison to their 17-10 victory over a powerful Tongan attack, during which the Georgians needed to stand firm to emerge triumphant.

Will Milton Haig's side have to take a greater grip on possession as they evolve? Absolutely. But a well-orchestrated scrum alongside a tackle tally of 185—more than five times Tonga's 36—did its job.

11. Samoa

Movement: None

Had the United States managed to find their kicking boots on Sunday morning, Samoa could have seen themselves with fewer than four points after Week 1, so a somewhat lucky escape doesn't see them move in the power rankings.

The likes of Alesana Tuilagi and Ofisa Treviranus are still around playing their brute roles, but the likes of Tim Nanai-Williams, Tusi Pisi and Kahn Fotuali'i give this Samoa team a more-polished sheen than has been previously seen.

10. Fiji

Movement: Down One

A 24-point margin of defeat did not do Fiji justice after they gave England a run for their money at Twickenham on Friday.

In the end, it was a fitness disadvantage which saw John McKee's side falter, but the Pacific Islanders won't discount their chances to progress just yet.

It was noted at the time that Fiji did superbly to challenge their hosts in the turnover share, and a 35-11 loss won't stop them from gleaning their share of positives ahead of a make-or-break clash with Australia on Wednesday.

9. South Africa

Movement: Down Two

Going from third to sixth in the World Rugby pecking order as a result of their surprise defeat to Japan, South Africa is in a state of shock after see the Springboks suffer their most-stunning loss.

And that's not discounting near misses in the past against fellow titans of the world, but this was an entirely different brand of upset—a game even South Africa coach Heyneke Meyer might have considered sewn up prior to kick-off.

South Africa sports minister Fikile Mbalula even went as far as to proclaim Meyer's men will be branded "losers" should they fail to beat Samoa this Saturday, per John Westerby of the Times.

8. Argentina

Movement: None

Almost any team in the world can be forgiven for a defeat to New Zealand, and Argentina's wait for a maiden victory over the All Blacks lingers on following a 16-26 loss at Wembley on Sunday.

The Pumas are again showing signs of improvement, though, after heading in at the half-time break with a 13-12 lead and, ultimately, just falling short against the might of Steve Hansen's bench.

Daniel Hourcade's side are unfortunate not to move up our list following a terrifically gutsy outing.

7. Japan

Movement: Up Six

Call it over-reaction. Call it the cause of the underdog. Call it whatever you want, but there's no doubting the fact Japan's first win against a tier-one nation outside their own borders puts the Brave Blossoms in an entirely new realm of rugby pedigree.

The Telegraph's Mick Cleary dubbed it the "greatest upset in World Cup history", while Ben Dirs of BBC Sport labelled this most unique result "a miracle."

Eddie Jones' superbly regimented outfit have succeeded in showing this tournament is there to be grasped by any nation.

Japan deservedly shoot up to 11th in the World Rugby rankings as a result.

6. Wales

Movement: None

Wales coach Warren Gatland may be pleased never to see another flat pass again in his life after being left frustrated by his side's lack of attacking incision during their rout of Uruguay.

Although Wales' eight tries were split equally across the two halves, it was only in the second period when opposition legs were tiring that they began to take full advantage of their opportunities.

Of course, a bonus-point win in their opening game is as effective as it gets, but the Welsh certainly have major need for improvement ahead of Saturday's crunch clash against England at Twickenham.

5. Australia

Kamil Krzaczynski/Associated Press

Movement: Down Two

The Wallabies are another team who fall down down the rankings due to the improvements of those around them, despite not kicking a ball at the Rugby World Cup so far.

Australia head coach Michael Cheika has been put on "red alert" following Japan's upset against the Springboks, according to the Telegraph's Jonathan Liew, but the 2015 Rugby Championship winners are still fully capable of topping Pool A.

4. France

Movement: Up One

Time and again, team selection has been outlined as the factor holding France back from recapturing their glory years, but a 32-10 trouncing of Italy on Saturday suggests coach Philippe Saint-Andre may be on to something.

The team operated more smoothly with Frederic Michalak in the No. 10 jersey, and while they would have liked to build on a tally of just two tries, Les Bleus made a bright start to their World Cup campaign.

But Yoann Huget sustained a knee injury during the opener to rule him out of the tournament, as BBC Sport reported, which is a huge blow for Saint-Andre and France.

2= England

Movement: None

It would be harsh to set England back after grinding out a tough-fought win against Fiji on Friday, so the Red Rose keeps their place in second, although they share it this time round.

Ireland had the benefit of a much-easier opening match with the 50-7 win over Canada and deservedly move up, but Stuart Lancaster's men showed grit to see off John McKee's side and grab a last-minute bonus point.

Nobody would say England's quarter-final place is safe just yet given games against Wales and Australia are still to come, but the foundation has certainly been laid to move on from the group.

2= Ireland

Movement: Up One

Matching England for that second spot comes Ireland, who demonstrated the smoothness throughout their backs fans have been yearning to see for a few years.

The 50-7 win on Saturday will, understandably, be met with the response this was a poor Canadian team they bulldozed from their path, but after the slow start against the United States in 2011, it was a welcome demonstration of Irish force.

Seven tries from seven different players speaks well of the depth Joe Schmidt possesses among his ranks, and despite being just about a full-strength side against Canada, there are reserves waiting to enhance the team.

1. New Zealand

Movement: None

How often have we seen this New Zealand team endure a sub-par first-half performance only to step things up in the second period? Not for the first time under Steve Hansen's reign, that was precisely the script which unfolded against Argentina.

The All Blacks came into this tournament following a successful defence of their Bledisloe Cup, and although a more dominant result may have been preferred, the team can take satisfaction at being made to fight for their 26-16 win on Sunday.

New Zealand enjoyed a 77 percent majority of territory in the second period and utilised their bench resources to good effect, beating twice as many defenders (36) as opponents Argentina in total (18).

All statistics come courtesy of ESPN Scrum.