How the final act of the 2017 Six Nations could change the 2019 World Cup

The Irish should be cheering on the French this weekend. More weirdly, and depending on what happens in Paris, Welsh rugby fans may actually WANT England to win the Grand Slam. Here's why...

The Six Nations championship – and the destination of the wooden spoon – may have been decided a week early, but this final round of matches is no dead rubber.

What happens in Edinburgh, Paris and Dublin this weekend could shape events in Kyoto, Japan, on May 10, as international rugby's very own, very specific chaos butterfly flaps its wings for the final time before the draw for the 2019 World Cup takes place.

Similar to its more commonly known chaos theory cousin, the hurricane butterfly, what lepidoptera rugbychaotica does this weekend in those three European cities could have a big effect on the other side of the world in several weeks' time.

Thanks to their top-three pool finishes in the 2015 World Cup, all the Six Nations and Rugby Championship sides, as well as Japan and Georgia, are included in the draw. Fiji, currently ranked 10th have yet to qualify.

The 12 sides will be split into three groups of four based on World Rugby's rankings on May 10, which will not change from the rankings decided, following this weekend's matches. Using current standings, the 12 confirmed teams at Japan 2019 breakdown as follows:

Draw Tier 1: New Zealand, England, Australia, Ireland

Draw Tier 2: Scotland, Wales, South Africa, France

Draw Tier 3: Argentina, Japan, Georgia, Italy

Two further tiers for teams yet to qualify from their tournaments will be included in the draw.

Tier 1 teams will be drawn first into four separate pools. Those four pools will be filled in turn by teams drawn from tier 2, then tier 3, and so on.

France and Wales meet in a match that could have the biggest impact on the all-important rankings. Rob Howley's Wales will take Ireland's top-four place - and their tier 1 slot - if they win in Paris and England complete the first-ever back-to-back Grand Slam in the 17-year history of the Six Nations in Dublin.

Meanwhile, if France loses by 15 points or more, they will drop one crucial place to ninth in World Rugby's rankings, surrendering their tier 2 slot to Argentina, and becoming all the more likely to be drawn in an impossible pool.

meanwhile, things may be looking good for Scotland, despite last week's shellacking by England, as Vern Cotter prepares to hand over the keys to the head coach's office to Gregor Townsend. Stern Vern's final match in charge is at home against Italy, and it has all the hallmarks of a big farewell party to the man who has restored a fair portion of Scottish pride to the rugby rank and file.

Ranking points are calculated using a formula based on opposing teams' current standings. As a result, Scotland, currently basking in their best World Rugby ranking of fifth, stand to gain no points no matter how well they beat 15th-placed Italy. Even if they lose a close game, they will remain in the top eight – which would mean they would be included in the second tier of teams in May's big draw. But, should the unthinkable happen and Italy win by 15 points or more, Scotland will drop to ninth. That would put them in the third tier for the draw.

And, as you have no doubt worked out, if Wales win in Paris, Ireland have to win in Dublin to preserve their top four, top-tier status.

All of which means that Irish fans, despite their shared Celtic bond with Wales, should probably support France in Paris. Of course, if Wales win, anyone heading into Cardiff city centre later one, could witness the strange sight and sound of Welsh rugby fans cheering and chanting – maybe even singing! – for England in the final match of 'Super Saturday'.

Such is the effect of international rugby's chaos butterfly.