Ireland and Argentina face a critical Pool A match at Adelaide Oval on Sunday, with both sides eyeing a place in the quarter finals.
Form guide
Ireland are undefeated so far, their run including decisive victories over Romania 45-17 and Namibia 64-7.
The match against the Pumas shapes as the toughest test for Ireland in the Tournament to date, a victory would ensure a place in the play offs.
Argentina have a bruising forward pack that put up a fight against Australia before losing 24-8.
The forwards showed in the 67-14 win over Namibia and the 50-3 defeat of Romania, a capacity to play a running style of rugby as well as their traditional set piece game.
Previous meetings
Argentina and Ireland have played each other five times with Ireland holding the advantage three games to two. All the Ireland wins have come at Lansdowne Road, including the most recent 16-7 victory in November 2002.
Argentina last beat ireland in Buenos Aires in June 2000.
The Pumas other victory came at Rugby World Cup 1999 when they recovered from 21-9 to beat Ireland 28-24 in the quarter final playoff.
In and Out:
One of the most noticeable selections is the return of David Humphreys at No.10 in place of Ronan O'Gara. Humphreys played as fly half when Ireland beat Romania 45-17 in their opening match of the tournament 11 days ago, while O'Gara, who drops back to the bench, played in the 64-7 defeat of Namibia on Sunday.
Flanker Keith Gleeson and Number 8 Eric Miller were both notable omissions. Miller, who has been in superb form in RWC 2003, is on the reserves bench, while Gleeson is out of the 22.
Coach Eddie O'Sullivan has beefed up his back row against the powerful Argentine's with Simon Eeasterby and Alan Quinlan both retaining their spots while Miller's place goes to 192cm, 118kg flanker Victor Costello. Outside centre Brian O'Driscoll and wing Denis Hickie (Ireland's top two try-scorers of all-time) lead Ireland's attack.
Argentina have made wholesale changes to the team that beat Romania with only right wing Jose Maria Nunez-Piossek retaining his starting position.
Key players
Ireland's talisman will once again be its dynamic hooker Keith Wood. The man from the province of Munster will captain his nation for the 34th time in his 56th Test appearance and needs only one more try to equal the record number of tries in Rugby World Cups by a forward.
He will need to marshall all the renowned fire of the Irish pack if they are to counter the massive Argentine eight.
Centre O'Driscoll, Ireland's other world class player, will need to be at his creative best to open scoring opportunities up out wide.
As ever the Pumas will be looking to its big men in the front row; Roberto Grau, Federico Mendez and Maurico Reggiardo to lay the scrum foundation around which so much Argentine success is based.
The combination of scrum half Augustin Pichot and points scoring fly half Gonzalo Quesada will need to turn possession into territory at ever opportunity to give the likes of Diego Albanese any chance out wide.
What it means
Put simply Argentina must win this game to have any chance of qualifying for the quarter finals.
They sit equal on top of Pool A with Ireland on 10 points, one clear of Australia in a three way tussle for two qualifying spots.
Both Ireland and Australia have a game in hand and if Ireland were to lose this match they could still qualkify by beating Australia at the Telstra Dome in Melbourne.
Argentina have no such second chance and must go for broke.
Besides the huge stakes, Ireland will be looking to erase the bitter memory of their defeat to Argentina at the last RWC.
What they said
Ireland coach Eddie O'Sullivan on selections in the backrow:
"I think the kind of game we'll play against Argentina is physical. We've gone for physicality and bulk in the backrow to match-up there. It is a reflection on the type of team we are playing and the type of game we'd like to play."
On Rugby World Cup elimination by Argentina in Lens, France 1999:
"I find it strange that we're still dealing with Lens. It was four years ago. I wasn't there and a lot of the team weren't there. A lot were. I'm not abdicating responsibility, but things have changed dramatically since then for both teams. Argentina are arguably the most improved team in world rugby. We're a better team as well. We're more focused on last November when we beat them."
On The Pumas' aggression:
"They'll be aggressive at scrum time, aggressive at maul time, aggressive in the tackles at the back. It will be a bruiser and it will be hand-to-hand combat. It won't be for the faint hearted."
On changes to Argentina's line-up:
"It does throw a few curve balls in there, but the Pumas are very clear about how they want to play the game. If they execute well they can beat any side in the world ... we can confuse ourselves looking for shadows that aren't really there."
On the selection of David Humphreys at number 10:
"There's the usual amount of debate about number 10, but it's like a broken record. At the moment David's in the driving seat by the skin of his teeth, but over two games it could go either way."
"Both are on top of their game, both are capable, but unfortunately I can only put one of them out there".
On Brian O'Driscoll:
"People are looking for Brian O'Driscoll to break lines, but as your name gets bigger the gaps get smaller. He's got to focus on putting other players into space ... if they want to shut him down then the other players will get into the spaces."
Ireland captain Keith Wood on speculation of a grudge match:
"I don't think it is a grudge match. You have to get your head around the concept of what happened back then. We beat them a month before the World Cup then we lost to them by playing really poorly. A lot of people disregarded Argentina."
Match details
Argentina v Ireland
Adelaide Oval, Adelaide
Kick off: 18:00 local time
Match Officials:
Referee: Andre Watson (South Africa)
Touch judges: Paddy O’Brien (New Zealand) and Nigel Whitehouse (Wales)
Television match official: Mark Lawrence (South Africa)