That complicates matters.

Scotland's 61-0 win over Russia puts them in the driving seat in the event of three teams finishing tied on points at the top of Pool A.

What it doesn’t change from Ireland’s point of view is that a bonus-point win for Joe Schmidt’s men against Samoa on Saturday will seal a place in the quarter-finals.

After that they can just sit back and relax in complete comfort knowing that they are assured of facing either the current and back-to-back World Cup winners or the Rugby Championship title holders.

New Zealand have scored 22 tries in their three pool games so far, while South Africa have 27.

There is a plausible set of results, however, that would mean Ireland could be eliminated at the group stage for just the second time in Rugby World Cup history.

It would require Ireland to beat Samoa without a bonus point, meaning they finish with 15 points, a tally achievable by both Japan and Scotland.

If Japan lose and get a bonus points (either by scoring four tries or losing by seven or fewer), and Scotland win with a bonus point then all three will have 15 points.

In this event, and when all three have beaten one another, it comes down to points difference. 

Scotland, at +71 (plus whatever margin they beat Japan by, providing they win with a bonus point on Sunday) are now ahead of Ireland (+52 plus margin of victory over Samoa) and Japan (+46).

If this remains the case after the final pool game then Scotland qualify in first place but we then revert to head-to-head record to decide second and third places, and Ireland, courtesy of losing to Japan, would go home.

Ireland are now 19 behind Scotland in the points difference column so could make that up and add more against Samoa, which would again change the dynamic of the pool. 

Scotland scored nine tries against Russia

Here we go though the numbers. 

If Ireland beat Samoa with a bonus point they will total 16 points and

Qualify for a quarter-final.

Qualify in first place if Japan are beaten and don't get two losing bonus points.

Qualify in second place if Japan simply beat or draw with Scotland.

If Ireland beat Samoa without getting a bonus point they will total 15 points and

Qualify in first place if Scotland beat Japan without allowing the hosts a bonus point.

Qualify in second place if Japan simply beat or draw with Scotland.

Qualify for quarter final unless Scotland (having overtaken both teams on points difference) and Japan also finish on 15.

If Ireland draw with Samoa and get three match points (2 for draw plus 1 for 4 tries) they will total 14 points and

Qualify in second place if Japan simply beat or draw with Scotland.

Be knocked out if Japan lose to Scotland, with both claiming bonus points.  

If Ireland draw with Samoa without a try-bonus point they will total 13 points and

Qualify for quarter-final in second place if Japan beat Scotland.

Be knocked out if Scotland beat Japan.

If Ireland lose to Samoa with a bonus point they will total 12 points and

Qualify in second place if Scotland don’t get more than two points (win or draw with four tries) against Japan.

Be knocked out if Scotland (after beating Russia with a bonus point) beat or get three points against Japan.

If Ireland lose to Samoa without a bonus point they will total 11 points and

Qualify for quarter-final if Scotland get less than two points against Japan.

Be knocked out if Scotland draw with or beat Japan, or lose with two bonus points. 

Be knocked out if Japan-Scotland is cancelled with both teams getting two points. 

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Follow Ireland v Samoa on Saturday 12 October (kick-off 11.45am) via the live blog on RTÉ.ie/Sport and the News Now App, watch live on RTÉ2 or listen to live match commentary on RTÉ 2fm.