The Six Nations leaders have started strongly in the 2014 Championship, but success hinges on their visit to Twickenham.
A dodgy opening 40 minutes against Scotland aside, Ireland have been the team of the tournament so far based on the way they picked off Scotland and then dismantled Wales in Dublin.
Having a home start is hugely beneficial for building confidence and momentum and Ireland now have both in abundance, a knock-on effect from the way they pushed New Zealand close last November. The pre-tournament concern was whether Ireland could match that the intensity of that performance against the All Blacks - so far they have delivered.
Joe Schmidt's influence has been obvious in the way Ireland tactically broke down Wales' Plan A and uncovered a lack of Plan B. It was astute, relentless and brilliantly executed, handing the champions their biggest loss in the Six Nations since 2006.
Individual performances have been key. Jonathan Sexton looks sharp, with his kicking game against Wales a huge factor in the suffocating gameplan designed by Schmidt.
Peter O'Mahony is in the form of his life, a nightmare to contain at the ruck area along with making an impact with his carrying and defence.
Add into the mix those British and Lions whose tour to Australia did not go as planned - Cian Healy, Jamie Heaslip, Rob Kearney, Brian O'Driscoll - and you have a burning desire from these players to remind the wider public of how good they are. A fine supporting cast consisting of Chris Henry, Devin Toner, Andrew Trimble and Dave Kearney are all putting their hands up too.
There is, of course, another O'Driscoll factor to contend with. Rory Best after the win over Wales summed up the pre-match furore over the fallout with Warren Gatland on the Lions tour by describing it as unspoken in the Ireland camp, but not ignored.
The same goes for O'Driscoll's impending retirement - a moment that will be sad for rugby fans the world over, not just in Ireland.
A player of his talent and status in the history of the sport deserves a second Six Nations championship to his name. 2014 may even finish in a second Grand Slam. Just as the Ireland camp may not voice publicly this being O'Driscoll's last Six Nations as a source of inspiration, with the focus on the team, doesn't mean it will not weigh on the mind.
That said, no one embodies the team ethos more than O'Driscoll himself. The line breaks have gradually dried up but the tackle and ruck counts have risen. The national intake of breath when he went down after a big tackle from Scott Williams underlined his value. He still offers so much, but as a warrior, not in the same blockbuster manner as a George North or an Israel Folau.
It is O'Driscoll's experience, supplying a fair share of the 700 plus caps Ireland will take to London next weekend, that gives them an edge over the other team unbeaten so far this year, France.
Philippe Saint-André's side also have two wins from two at home, putting their fans through the wringer against England before flicking on the afterburners against Italy.
Their inconsistency though plays against them, as does a trip to face a wounded Wales on Friday, but they are back in the mix.
England's task was always going to be harder after losing the first game, but Stuart Lancaster's team did a professional job on Scotland despite leaving tries out on the field.
Perhaps if the Murrayfield pitch had been anywhere near up to standard then their performance would have rated as spectacular rather than satisfactory.
The key to English success lies in the forwards, who for periods of the second half against France where unplayable, epitomised by the carrying of Billy Vunipola.
Now England are back at Twickenham, where they have won five of their last seven matches including victories against New Zealand and Australia. Their attack has improved, the young pack exudes confidence, and Danny Care is bringing the best out of Owen Farrell.
Calling the outcome of next Saturday at Twickenham is not simple, with a single score likely to decide matters. Should Ireland win, with a home game against Italy and travelling to Paris to come, the Slam is very much on.
If England succeed, then we will be going down to the final day with perhaps two or three teams in contention for the title. For now though, after an encouraging and impressive start, Schmidt and Ireland hold pole position.
by Ben Coles