Fit again Ospreys wing Shane Williams returns to the back three sparking a positional switch for Scarlets wing George North, who moves from left to right wing to accommodate Wales' all-time top try scorer, and for Blues flier Leigh Halfpenny, who moves from wing to full back at the expense of Clermont's Lee Byrne.

In the centres Jonathan Davies returns to partner Jamie Roberts, with his regional team-mate at the Scarlets, Scott Williams, moving to the bench.

Up front Dragons back row forward Dan Lydiate completes his return from the ankle injury he picked up in Round 2, replacing Osprey Ryan Jones, who also provides cover from the bench.

The final change comes in the second row with Osprey Alun Wyn Jones promoted from bench duty to partner Dragon Luke Charteris, with Blues lock Bradley Davies again retained as a replacement.

Elsewhere on the bench James Hook completes his return from injury to replace Stephen Jones, who is omitted alongside Byrne, to join Williams and Blues scrum half Lloyd Williams in providing cover for the backs.

Ospreys prop Paul James and Dragons hooker Lloyd Burns are retained to provide front row cover alongside lock Davies and flanker Jones.

That means it's 'same again' for the front row of Gethin Jenkins (Blues), Huw Bennett and Adam Jones (both Ospreys), half backs Mike Phillips (Bayonne) and Rhys Priestland (Scarlets), with Dragon Toby Faletau also retained in the back row alongside captain Sam Warburton (Blues).

"This was a tough selection for us, probably one of the longest selection meetings we have ever had, where we went through every possible permutation available to us," said Wales coach Warren Gatland.

"It's a great position to be in when you are struggling to find a place for players in the squad and the starting line-up, instead of having to think who can make up the numbers, which has sometimes been the case.

"This is Rugby World Cup quarter-final time and we had some tough decisions to make with the likes of Dan, Shane and James returning from injury and the side having done so well in their recent absence.

"But this is the side we have gone with and, as a 22, we believe it is the side which gives us the best chance of winning this game against an Ireland team which not only topped their group but beat the Wallabies on the way."

WALES: Leigh Halfpenny; George North, Jonathan Davies, Jamie Roberts, Shane Williams, Rhys Priestland, Mike Phillips; Gethin Jenkins, Huw Bennett, Adam Jones, Luke Charteris, Alun Wyn Jones, Dan Lydiate Sam Warburton (captain), Toby Faletau
REPLACEMENTS: Lloyd Burns, Paul James, Bradley Davies, Ryan Jones, Lloyd Williams, James Hook, Scott Williams