The scrum is viewed as Ireland's Achilles heel with Wales coach Gareth Jenkins admitting the Triple Crown holders' front row will be targeted at the Millennium Stadium today.

Destructive props Chris Horsman and Gethin Jenkins are expected to trouble John Hayes and Marcus Horan, while the selection of Alix Popham and Ryan Jones in the back row adds beef.

O'Sullivan believes Wales will only look to play their famed running game once their forward assault has broken Ireland up-front.

"Wales know they are good at moving the ball so that's what they will try to do, " he said. "That's been their trademark for the last few years and they have been very successful at it.

"But if you look at their selection then it's evident they believe they will have to soften up our pack first. There's no secret what their plan will be - to stamp their authority on the match with their pack.

"Once they feel they have softened us up enough they will look to move the ball away. The battle lines have been drawn between the two packs but if Wales get the ball they will run with it."

Hayes' and Horan's problems in the scrum during Munster's Heineken Cup defeat by Leicester last month has only served to underline Ireland's greatest shortcoming. Wales are expected to gain an advantage in the front row and O'Sullivan admits scrummaging has been a key area in training this week.

"We always scrum live on the week of a Test game, that's why we have more people in camp, " he said.

"We haven't put a huge amount of effort into it, we've just been more selective about what we're doing.

There's a danger you'll leave your best energy on the training pitch. But we have paid a fair bit of attention to scrummaging."

Scrum-half Peter Stringer agrees that Ireland must meet Wales's expected early onslaught head-on.

"We were perhaps caught off guard in 2005. We have got to start the game a lot faster, " he said. "The pressure they put on us in that game and the occasion meant they were physically up for it.

"We have to match that, flip it over in the first 10-15 minutes and set out a stall and show them we will not be bullied. We have to get stuck into them."