Ireland coach Eddie O'Sullivan has warned his pack they must survive Wales' softening-up process if they are to make a successful start to the Six Nations.

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 tomorrow.

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 tomorrow - 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."

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 an opinion that scrummaging his just a lot grunt and hard work.

"There's an element of that but if you do that 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."

What Ireland lack in the scrum they make up for in other areas, namely the midfield where Brian O'Driscoll and Gordon D'Arcy are the most formidable centre partnership in Test rugby.

But in James Hook (21) they face a rising star who has enjoyed a sensational start to his international career and O'Sullivan is a keen admirer of the Ospreys back.

"The exciting thing about Hook is that he's hit the ground running since winning his first cap," he said.

"He seems to tick all the boxes as a rugby player. The most important box is his temperament because he's shown extraordinary composure since he's come on the scene.

"He's a player who has become an important cog in the Wales machine very quickly."

Wales talisman Gareth Thomas is unavailable after landing a four-week ban following an incident during Toulouse's controversial Heineken Cup clash with Ulster last month.

O'Driscoll knows Thomas from their time together on the 2005 Lions tour to New Zealand and insists his absence will leave a big hole in the Welsh team.

"Gareth is a major loss because he's been an instrumental for them for a number of years," said the Ireland skipper.

"I know Denis Hickie will be disappointed Gareth is not available because he wanted to play against someone who was older and balder than him!

"Gareth is such a great character and brings so much to the squad. It's not just his playing ability but the feelgood factor he generates in any team he's involved in.

"He'll be missed for the three game but will be welcomed back with open arms when he does return."  PA