ENGLAND'S selection at hooker for Sunday's Six Nations clash at the Aviva Stadium will reveal much about their plans for derailing Ireland's season.
If, as expected, the visitors opt for Dylan Hartley, their intention will be to target Mike Ross and the Ireland set-piece, believing that the tighthead prop is vulnerable and fragile after his experiences in Twickenham last season.
Ross had to be replaced because of a neck injury by Tom Court after 36 minutes of the contest, but England had been enjoying some gains in the scrums even before then. They were wholly dominant after Ross' departure, as Court's weaknesses as an international tighthead were exploited.
England, though, are of the belief that Ross is susceptible to concentrated targeting and in Hartley they have the perfect weapon in their arsenal to test their theory.
Even if England coach Stuart Lancaster opts to retain Tom Youngs at hooker, they will still aim for scrum dominance. But if Hartley is the pick then there will be no ambiguity. It will be as they are if trumpeting their intentions from the tree-tops with a bull-horn.
Joe Marler in the loosehead position and the hooker will spend the entire 80 minutes hunting Ross down.
Last year Ireland had the opportunity to finish the Six Nations on a high and take second place behind Wales. They travelled to Twickenham in confidence after smashing Scotland 32-14 in Dublin a week earlier, a result that built on their creditable draw with France in Paris.
The game in Twickenham will be remembered for two things. One, England won 30-9 pulling up. And two, it blew apart the fallacy that loosehead props can also be effective at tighthead.
The rules at the time allowed for match-day squads of 22 and two front-row options. Court was covering both propping positions, so when Ross succumbed to his neck injury, Court was pressed into service on the right-hand side of the scrum.
England's loosehead Alex Corbierso and Hartley destroyed the Ireland replacement tighthead. England won 11 of their 12 scrums and won three of Ireland's six. It was a massacre. Thankfully, the rules now allow for 23-man squads and specialist cover for all three front-row positions.
The biggest problem Ireland experienced last year was that while there have been successful conversions from tighthead to loosehead – Peter Clohessy being the most fruitful example – it is exceptionally rare for a loosehead to be able to switch to tighthead with any great success.
It adds to the legend that Clohessy switched sides unexpectedly when John Hayes came on the scene.
Hayes, in his book, tells of how he bluffed his ability to function as both a tighthead and a loosehead prop, but when he was sent on for his Munster debut in 1997 as a replacement for Ian Murray, he begged Clohessy to switch over because he had never played on the left-hand side of the scrum before.
"It extended my career, internationally and with Munster, for years," said Clohessy of that development.
The loosehead position is the easier of the two propping sides. The loosehead's job is to solidify his side of the scrum while also supporting his hooker on his 'strike' as well as attacking the opposition's tighthead.
The loosehead's head position is on the outside of the scrum whereas the tighthead's head position is in between the opposition's hooker and loosehead.
It takes a special kind of bravery to willingly commit to a position where two men are actively seeking to hurt you.
The tighthead prop must absorb far more pressure in the scrums than the loosehead, which is why it is easier to switch from tight to loose and not the other way around. The tighthead provides the foundation for the scrum, but there is more to it than that.
The tighthead cannot take a step back on his put-in. If he does the initiative is lost and it has a knock-on effect throughout the team. If the tighthead takes a step back then the scrum-half is scrambling to get the ball at the base, and in turn the out-half is taking a step back before receiving and so are those outside him.
It is to Ireland's advantage that Corbierso is ruled out for this game with a knee injury. Joe Marler is not as dominant a scrummager as the London Irish loosehead, which is why Hartley might well be preferred to Youngs at hooker this weekend.
Hartley is second only to Rory Best as a scrummaging hooker in this part of the world. He provides more firepower than Youngs and if, as expected, Lancaster opts for the Northampton hooker there will be no question of England's tactics: Ross will be targeted.
What England will do is attempt to force a two-on-one situation. They will pressure Best in the hope the hooker has to pop his head up so as to relieve the force being brought to bear.
Ireland are fortunate that Best is back to full fitness because he can absorb a ferocious amount of pressure, which will help keep the force off Ross.
Hartley, who captained Northampton in that final, gained notoriety last year when he was cited and subsequently banned for eight weeks for biting Stephen Ferris during the game. It was a reprehensible act and his punishment was outrageously lenient.
He was also cited and banned for two weeks when found guilty of striking Best with his forearm during Northampton's Heineken Cup defeat to Ulster at Franklin's Gardens in December.
He has a nasty streak to his game that makes him a bit of a liability selection wise because there is always the danger he will earn a yellow, or even red, card at some stage of the game. But if England are determined to attack Ireland's platform, he is just the man to unleash.
This is a hugely important game for both sides. After their opening-day victories they are both in the running for the championship, although given that France are the only side to ever lose their opening game and still win the title, a feat they achieved in 2006, they cannot be completely ruled out of the equation.
Ireland and England are, though, in better positions and one of them should be in an infinitely stronger position on Sunday evening.
It is now 10 years since England last won in Dublin, a record the current generation will be loath to see broken on their watch.