Rugby:Just one week into the Six Nations and Ireland's clash with England this Sunday already stands out as being pivotal to the destiny of the title. It will not directly determine who wins the Grand Slam but it will certainly determine who will not. Ireland, England and Italy are the only teams who can still dream of a clean sweep.

The attacking threats Ireland will pose at the Aviva Stadium are multiple and varied: the dynamic ball-carrying of Sean O’Brien, the bewitching midfield brilliance of Brian O’Driscoll, the pace and footwork of wings Simon Zebo and Craig Gilroy. It is no surprise that England look set to retain defensive leader Brad Barritt in midfield rather than promote the fit-again Manu Tuilagi to partner Billy Twelvetrees. England need their tackling machine.

But it is also without the ball that Ireland pose a peculiar threat, with the choke tackle. The technique was devised by Ireland’s defence coach Les Kiss and, when executed well, it can squeeze the life out of teams, as England discovered to their cost in Dublin two years ago when their Grand Slam ambitions were destroyed.

Australia were also strangled by the Kiss technique at the 2011 Rugby World Cup in what is widely considered to be Ireland’s finest ever victory at a global tournament.

The traditional tackling technique is to get the ball carrier to ground and then look to steal possession at the breakdown. Ireland are not shabby at that, particularly with O’Driscoll acting as an auxiliary flanker. But the choke technique demands the opposite. A pair of defenders work together to clamp man and ball, keep him on his feet and turn the tackle into a maul. With the trapped ball not coming out, the attacking team lose possession. Turnover. Scrum, Ireland ball.

What may help England is that they are also looking to keep the ball moving, to pass before contact and constantly change the point of attack. If that keeps the defence wrong-footed there is less chance of two Irishmen pinning the ball-carrier on his feet. But there will be contact on Sunday, plenty of it, and England have had to prepare especially.

“What is crucial is your body height into contact and your support,” said England hooker Dylan Hartley, who conceded a turnover with his first carry in that 2011 Six Nations game after being pincered in a choke tackle. “If your support stands off for one or two seconds and expects you to get through and make an offload, you have lost the battle already.

“As soon as the man opts to go for the contact, you need to get your latchers on, get your weight behind them and the momentum. It is all down to the carry, if the carry is dominant you will win that. “But if you get it wrong, it is obvious what happens. You turn the ball over.”

As Hartley suggested, the choke tackle is not a perfect technique. There are ways of combating it and if successful the attacking team can profit by gaining extra territory.

“It obviously has its benefits but if you get it wrong you are going to concede metres,” Hartley said. “If one defender tries holding one man up and the ball-carrier gets two or three players behind him pushing then you are going to go backwards. That’s the flip side.”

But Kiss is content with that, knowing that while the opponents might be driving Ireland backwards they have also had to commit more attackers to the maul and therefore have reduced numbers out wide.

Ireland have plenty of attacking weapons in their arsenal, as do England. But it could come down to who has the best Kiss technique.