WALES (2nd) v IRELAND (4th), Millennium Stadium, 5pm (live RTÉ Two/BBC One)
Team News: Head coach Declan Kidney has named an unchanged starting line-up for Ireland's fourth game of the 2011 Championship.
The replacements bench also remains the same from the recent 21-18 win over Scotland, with Leo Cullen recovering from a slight groin problem.
Flanker David Wallace will win his 70th cap when he lines out alongside Jamie Heaslip and Sean O'Brien in the back row. It will also be his 40th appearance in the Championship.
Speaking on team announcement day, Kidney said: "Everything points to there not being a lot being between ourselves and Wales. We've a huge game ahead of us.
"Going to Cardiff, depending on what era you're from, it was always a daunting task at Cardiff Arms Park. Myself, I was more JPR Williams and Barry John's time and you always knew it was going to be a tough game at the Cardiff Arms.
"When we played them at the Millennium Stadium two years ago, there was literally that one kick of the ball between the sides.
"These lads play each other three times a year - at least twice in the domestic league and then at this level - and the fact that they know each other so well, space is going to be at a premium.
"It will be one of those games that whoever takes their chances will come out on top."
Meanwhile, Wales head coach Warren Gatland has brought Leigh Halfpenny and Jonathan Davies into the starting line-up for the visit of Ireland.
The Welsh pack from the 24-16 win over Italy remains unchanged, but there are four alterations - two of them positional - to the back-line.
James Hook moves from outside centre to out-half, where he started against Scotland last month, as Jonathan Davies returns from a hamstring injury to reform his centre partnership with Jamie Roberts.
Leigh Halfpenny replaces Morgan Stoddart on the right wing, with Stoddart dropping to a replacements bench which also includes Stephen Jones, Dwayne Peel, Richard Hibbard and John Yapp.
Scrum half Mike Phillips and his Ospreys team-mate Ryan Jones will start against Ireland, winning their 50th caps for Wales.
Head coach Warren Gatland said: "This is a crucial game for us as a win will keep us in the Championship mix and take us into that final round with everything still to play for. But it is also a big game for Ireland who are in a similar position to us going into this match."
Forwards coach Robin McBryde added: "The forwards had a tough day at the office in Italy and we were not at our very best so we are looking for a step up in performance this weekend.
"Ireland will be tough, they have a well-drilled set piece game, are good around the field and are strong defensively.
"They bring intensity to the breakdown area which is always so crucial in these big games and it will be up to us to match them if we are going to be able to provide a platform for our exciting backs to play."
WALES: Lee Byrne (Ospreys); Leigh Halfpenny (Cardiff Blues), Jamie Roberts (Cardiff Blues), Jonathan Davies (Scarlets), Shane Williams (Ospreys); James Hook (Ospreys), Mike Phillips (Ospreys); Paul James (Ospreys), Matthew Rees (Scarlets) (capt), Craig Mitchell (Ospreys), Bradley Davies (Cardiff Blues), Alun Wyn Jones (Ospreys), Dan Lydiate (Newport Gwent Dragons), Sam Warburton (Cardiff Blues), Ryan Jones (Ospreys).
Replacements: Richard Hibbard (Ospreys), John Yapp (Cardiff Blues), Jonathan Thomas (Ospreys), Rob McCusker (Scarlets), Dwayne Peel (Sale Sharks), Stephen Jones (Scarlets), Morgan Stoddart (Scarlets).
IRELAND: Luke Fitzgerald (Blackrock College/Leinster); Tommy Bowe (Ospreys), Brian O'Driscoll (UCD/Leinster) (capt), Gordon D'Arcy (Lansdowne/Leinster), Keith Earls (Thomond/Munster); Ronan O'Gara (Cork Constitution/Munster), Eoin Reddan (Lansdowne/Leinster); Cian Healy (Clontarf/Leinster), Rory Best (Banbridge/Ulster), Mike Ross (Clontarf/Leinster), Donncha O'Callaghan (Cork Constitution/Munster), Paul O'Connell (Young Munster/Munster), Sean O'Brien (Clontarf/Leinster), David Wallace (Garryowen/Munster), Jamie Heaslip (Naas/Leinster).
Replacements: Sean Cronin (Buccaneers/Connacht), Tom Court (Malone/Ulster), Leo Cullen (Blackrock College/Leinster), Denis Leamy (Cork Constitution/Munster), Peter Stringer (Shannon/Munster), Jonathan Sexton (St. Mary's College/Leinster), Paddy Wallace (Ballymena/Ulster).
Referee: Jonathan Kaplan (South Africa)
Assistant Referees: Craig Joubert (South Africa), Peter Allan (Scotland)
Television Match Official: Geoff Warren (England)
Match Odds (Paddy Power): Wales to win: 5/6; Draw: 20/1; Ireland to win: 11/10
Pre-Match Quotes: Brian O'Driscoll (Ireland) - "I think we've gotten out of third gear in some of our attacking play, just other parts of our play have let us down. We've scored good tries, we just have to be a little more consistent over an 80-minute period.
"Test matches will always be close if you only play for 40 and allow the other team to play for 40, which is essentially what we've done. We must be a bit more commanding in our own play and when we have hold of the ball, and be a little better when we don't.
"(The Millennium Stadium) is very, very loud and is definitely one of the best stadiums in the world to play in because of the atmosphere and the noise generated there. The crowd is right in on top of you.
"It's not somewhere we love going to, but it's not somewhere that we fear going to. It's a game that's up for grabs depending on whether you play better than the opposition. And they're the sort of odds you want going into any game.
"A lot of guys who have played there before have good memories. The Munster boys won two Heineken Cups there while we have a Grand Slam to remember from the last time we were in Cardiff.
"All we can do is try to win our last two games and with regards to points differences and stuff, that has no bearing on you when you have a game this weekend and then one to go the following week.
"What is attainable is that we can still chase silverware in terms of a Triple Crown and the second part of that is this weekend, so there's no point in thinking about the third part of it if we slip up in the second part."
Matthew Rees (Wales) - "The Millennium Stadiums has the X factor and there is no better stadium to run out in anywhere in the world.
"It was great for us to win back-to-back games on the road as it is a tough ask in the Six Nations, but we have to kick on from the last few weeks.
"We are now up to second in the table and it's a great place at the moment but international rugby is all about winning.
"We have to make sure we are accurate, make sure we are not turned over and our discipline has to be spot on as Ronan O'Gara has been around for a long time and is one of the best kickers in the world.
"It's going to be tough up front but we have to concentrate on ourselves. Our scrum came under a bit of pressure out in Italy but we worked on that in the week and it's important that we get a platform.
"The pressure is on us on Saturday, and the biggest issue for us is our own mistakes. We have to make sure we are accurate, disciplined and not make mistakes.
"The one thing that has frustrated me about us in the Six Nations is ourselves. We had two yellow cards against Scotland, which is unacceptable, and we gifted Italy two tries and we kept them in the game with ill-discipline.
"The message for us against Ireland is that we need to perform well for more than just 20 minutes. That is our biggest challenge, and if we can do that then I am sure the result will take care of itself."
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