Six Nations 2015: Scotland v Ireland preview
Ireland's chances of a Grand Slam have gone, but they still have a shot at retaining their title – if they score enough...
Six Nations 2015: Scotland v Ireland, kick-off 2:30pm BBC1
Keith Wood said right at the start of the Six Nations that the competition was too tight for any one nation to win a Grand Slam this year, and so it has proved – although for a long time Ireland looked like they might have surprised their former captain.
The Irish finally came unstuck against a resurgent Wales in Cardiff last week. Coach Joe Schmidt's meticulous preparation was not enough to beat the nerve-shredding effectiveness of his fellow New Zealander and opposite number Warren Gatland. His Wales won the day.
Scotland, winless and wounded, have been badly lacking in the kind of game efficiency that Ireland have displayed under Schmidt. They reached a new low in their home loss to Italy, and for all their pre-tournament optimism the Scots have a lot of gaps to plug before the Rugby World Cup later this year.
Quietly impressive captain Greig Laidlaw will desperately want to finish on a high, but the reality is Scotland's thin squad probably don't yet have the big game nous to make an advantage stick.
Ireland might not be scoring many tries (just four compared to England's 11), but with scrum half Conor Murray and fly half Jonathan Sexton controlling every facet of play, the squad have gone about defending their Six Nations crown with steady determination.
Today, however, will be different. They will know what they have to do to finish ahead of Wales, but with England playing straight after them they are in a quandary. Do they go for broke, open out their play in the search for a big win, but risk a Scottish upset?
Or do they stick to their minimalist game plan, get the job done and leave the pressure on England to match them later in the afternoon?
Schmidt has outsmarted many of his rivals since taking over in 2013 – but Saturday's permutations will be the toughest exam yet.