Ben Dirs
BBC Sport at the Millennium Stadium

"The Irish have found full voice now, 'The Fields of Athenry' ringing out around the Millennium Stadium. But what's this? The Argentines quickly drown them out with some songs of their own. It's already epic in Cardiff, and we haven't even kicked off yet. Stand by for a classic." 

Image source, EPA

Oh my, the salty tears are flowing from Argentina's players even before their national anthem kicks into full swing. It's as if someone's put a picture of their deceased childhood pets up on the big screen. 

Next it's Ireland's turn to add their voice to proceedings and the men in green win the singing contest. Paul O'Connell singing along from the stands, standing with the aid of crutches. 

Stirring stuff. 

Image source, AFP

Image source, AP

Cries of "ole!" rings around the Millennium Stadium, both sets of fans creating a crackling atmosphere. 

The two teams in the bowels of the stadium, awaiting their call to march out from under the tunnel and into a wall of noise.

Justin Marshall
Former New Zealand scrum-half on BBC Radio 5 live

"It would be good for the tournament if Ireland made the semi-finals. If the last four are all southern hemisphere teams, that makes it more difficult. 

"But it's not the end of the world for rugby union of there are no northern hemisphere teams in the semi-finals, though, because the best teams need to win. I think this has been the most competitive Rugby World Cup I've seen, and that's great for the game."

Image source, AFP

Denis Hickie
Former Ireland winger on BBC Radio 5 live

"One of my best rugby memories is in 2003, at the Adelaide Oval, when we beat Argentina to make it through the pool stages at their expense. One of my worst memories is 2007, when Argentina knocked us out. 

"Argentina were just better than us that day. This team are slightly different. There's more to Argentina's game now. People ask: How do Argentina play? Think France 20 years ago. They've a big strong pack and a huge willingness to move the ball. They're a very well balanced side."

John Haughey
BBC Sport at the Millennium Stadium

"Paul O’Connell is not going to be on the pitch for Ireland but his former team-mate and BBC Sport NI columnist Stephen Ferris is expecting the big man to play a role in rallying the troops before today’s game.

"The Munster legend's speeches regularly bring tears to the eyes of team-mates so goodness knows what Paulie has planned for today’s occasion as Ireland aim to qualify for a first ever World Cup semi-final."

Ireland lock Dan Tuohy on BBC Radio Ulster: “As was the case in the first two quarter-finals, physicality around the breakdown is probably going to decide the outcome today but I think Ireland should still be massively confident despite all their injuries and Sean O’Brien’s ban.”

Argentina's last win against Ireland was in the 2007 World Cup when they won 30-15 in the group stages.

But since then the Pumas' record against the Irish reads played five, lost five. Should the Irish take heart from that? 

Image source, BBC Sport

Justin Marshall
Former New Zealand scrum-half on BBC Radio 5 live

"Argentina are dangerous across the park. They gave New Zealand problems with their brutality in the first game. They've got some subtleties in the back line, too. They'll miss Marcelo Bosch, though."

Former Scotland international Rory Lawson wishes Ireland well and shares his predictions for the tournament.

Justin Marshall
Former New Zealand scrum-half on BBC Radio 5 live

"Having Paul O'Connell around today does a lot for Ireland, even though he can't play. He's an icon of Irish rugby. The All Blacks did that with Tony Woodcock - he hasn't gone home either. Having players around like that is an inspiration. Just having him there, knowing he's watching, knowing how high his standards are, can make a difference."

Image source, Getty Images

The Millennium Stadium is gradually filling up, fans leaving the bars, sipping the remaining dregs from their pints, to find their precious seats. 

Paul O'Connell, hobbling on crutches, is on the sidelines, chatting and watching his team-mates warm up. He's been there for quite a while. They might have to drag him from the pitch. 

Oh what would he give to be going into battle with his band of brothers today. 

Suspended centre Marcelo Bosch is the only regular name missing from the Argentina line-up, having been banned for a week for committing a dangerous tackle against Namibia in Argentina's final pool game.

He is replaced by Matias Moroni, one of 10 changes made by Argentina coach Daniel Hourcade for the Ireland game.

Many of the leading players rested for the Pool C game against Namibia return, with scrum-half Martin Landajo starting ahead of Tomas Cubelli to win his 50th cap.

Image source, BBC Sport

Wales' capital has turned green for the afternoon. But that isn't to say there are a number of Pumas lurking around the streets and, as we know from previous games in this tournament, Argentina fans know how to turn up the volume. They have plenty of bite those Puma fans. 

John Haughey
BBC Sport at the Millennium Stadium

"Where to start with Ireland? Johnny Sexton was ruled out on Saturday morning because of what was described as an abductor muscle injury. More commonly known as a groin strain, I think.

"Ian Madigan, who came on for the injured fly-half after 26 minutes last weekend, replaces Sexton.

"Iain Henderson replaces hamstrung Paul O’Connell at lock, with Chris Henry and Jordi Murphy taking over from injured Peter O’Mahony and banned Sean O’Brien in the back row."

Image source, BBC Sport

It's a battle between north and south, one hemisphere against the other, and if Ireland lose this one it could be very grim up north indeed. 

Two southern hemisphere sides have already made sure of their semi-final places. Victory for Argentina today would be another one up for the Rugby Championship on the Six Nations. 

For those of you who enjoy looking at the history books to predict the future. These sides have met three times at the World Cup, with Argentina winning on two occasions and Ireland one. It's close.