Live Commentary: Ireland 20-43 Argentina - as it happened

Good afternoon! Ireland will be hoping to reach the Rugby World Cup semi-finals for the first time when they take on Argentina this afternoon. The Pumas have looked in good form in the pool phase though, suffering their only loss against reigning champions New Zealand. Let's start with a reminder of the lineups.

IRELAND STARTING XV: R Kearney, Bowe, Earls, Henshaw, D Kearney, Madigan, Murray, Healy, Best, Ross, Henderson, Toner, Murphy, Henry, Heaslip

ARGENTINA STARTING XV: Tuculet, Cordero, Moroni, Hernandez, Imhoff, Sanchez, Landajo, Ayerza, Creevy, Herrera, Petti, Lavanini, Matera, Lobbe, Senatore

Ireland have been forced to make a few changes to the side that beat France last weekend. Despite initially being included in the starting lineup, fly-half Johnny Sexton has had to pull out with an adductor strain, while Paul O'Connell and Peter O'Mahony will both miss the rest of the tournament. Ian Madigan starts at fly-half, while Jordi Murphy and Iain Henderson also come in. There's a change at flanker too as Sean O'Brien is suspended, making way for Chris Henry.

Argentina were last in action against Pool C minnow Namibia, who they thrashed 64-19, so unsurprisingly there are plenty of changes for the Pumas. Daniel Hourcade makes 10 changes, naming a side that have 496 caps in total. Tomas Lavinini and Juan Martin Fernandez Lobbe are among those to come back in after being rested last time out, while Martin Landajo continues at scrum-half, earning his 50th cap for the country.

Ireland have played a couple of matches in Cardiff already, receiving an impressive level of support. The Irish fans appear to be out in force again this afternoon:

Ireland supporters gather at the team bus. #shouldertoshoulder #rwc2015 #emotional pic.twitter.com/9UUN3dDVWz

— Irish Rugby (@IrishRugby) October 18, 2015

Ahead of this match, Ireland coach Joe Schmidt said of O'Brien's suspension: "What you hope to do is learn from experiences. You learn from experiences win, lose or draw and hopefully we've learnt a lesson from that. You know, the fact the same player did it in the 49th minute adds to our frustration and Sean didn't react that time. Probably because we were only a few metres out from the line; he loaded himself to carry the next ball and did it incredibly well."

Meanwhile, Daniel Hourcade said at his pre-match press conference: "They are the rivals from the north who most play like the teams of the south and showed it with their recent results, especially winning the last two Six Nations in great manner."

The quarter-finals haven't gone too well for the Northern hemisphere sides so far, with France and Wales bowing out at the hands of New Zealand and South Africa respectively yesterday. With Scotland facing a tricky tie against Australia later today, the pressure is really on the Six Nations champions to represent the north.

Sports Mole's Dan Lewis is back at the Millennium Stadium today, having watched New Zealand thrash France there last night. Here are his thoughts ahead of kickoff:

"Well last night we witnessed a real masterclass from the reigning world champs at the Millennium Stadium, but today's contest should be a lot tighter - on paper at least!

"Having watched both these sides up close already at this year's competition, it's fair to say that there is not a great deal between them. Ireland outnumber their opponents by about 5:1 this afternoon, though, which could play a huge part."

In 15 previous meetings between the two sides, Ireland have secured the majority of the wins, claiming 10 victories. They've met three times before at the Rugby World Cup though, with Argentina beating them twice. In fact, seven of Ireland's 10 wins against Argentina have come on home soil. Given the level of support for Ireland in Cardiff this afternoon, this should feel like a home fixture though.

In fact, Ireland have won their five matches against Argentina, having last been beaten by the Pumas at the 2007 World Cup, where Argentina went on to finish third. Their last meeting was pretty close though, with Ireland clinching a 23-17 win in Argentina last June.

Despite beating France 24-9 last time out, Ireland did suffer a big loss last Sunday, with captain Paul O'Connell picking up a hamstring injury which rules him out for the rest of the World Cup. The flanker had already announced that he plans to retire from international after this tournament, so the injury ends his career with Ireland. As a result, Jamie Heaslip will be captain for this match.

Here's some more from Dan Lewis at the Millennium Stadium:

"This is Ireland's sixth appearance at this stage of the competition, yet they have never managed to win in the knockout round. That is a quite astonishing hoodoo that they will be looking to put right this afternoon.

"For Argentina, they have better pedigree having finished third eight years ago, but matching that feat this time around may be just out of reach."

Ireland captain Jamie Heaslip is backing Ian Madigan to perform in Johnny Sexton's absence: "I know Johnny's gutted but he's also helping Ian prepare and doing everything for that. But it doesn't change the gameplan at all with Ian in there. You saw last week when Johnny came off Ian stepped in and we all get the same gameplan we run through the week. He stepped right in and did a great job. Ian's taken his opportunity every time he's been called up, and he will do that again."

Former Argentina football star Diego Maradona has been supporting the country's rugby team, watching their win over Tonga earlier this month at the King Power Stadium in Leicester. Captain Agustin Creevy reveals that the FIFA World Cup winner will be back if they reach the last four: "He told us that if we get to the semi-finals he will come. He took the number nine, 10 and two jerseys and gave us one of his. He told us that all of Argentina was dreaming with us, which is why he was here, why he wanted to be here. I never imagined he's come to see us."

The winner of this match will play their semi-final at Twickenham next Sunday, where they will face the winner of the last of the four quarter-finals between Australia and Scotland, which takes place later today.

Ireland will have to keep their eye on Argentine winger Santiago Cordero this afternoon. He made three appearances in the pool phase, scoring as many tries - only six players have scored more tries than Cordero at this year's tournament. Keith Earls and Rob Kearney also have three tries to their name though.

The players are starting to gather in the tunnel ready to head out for kickoff. The Millennium Stadium looks absolutely packed, and the atmosphere is really building. The action is just a few minutes away now.

The sides make their way out onto the pitch and the crowd erupts. Paul O'Connell is standing on crutches on the sideline for Ireland cheering his side on. As always, the anthems from both countries will be played ahead of kickoff.

There are tears from most of the Argentina squad as they sing along to their national anthem, but it's Ireland's Call that gets the crowd going, with the players and fans belting the song out with kickoff just moments away.

KICKOFF! Ian Madigan gets the action underway for Ireland.

What a start for Argentina! Tuculet gets the ball out from the back with a kick forward before Cordero passes it out to Matias Moroni, who is picking up just his seventh cap for the Pumas. Ireland were expecting a run through the middle, so didn't have numbers across, leaving the centre with an easy run across the line.

Dan Lewis reports on the opening few minutes of the match:

"Having been lucky enough to attend eight games at this Rugby World Cup - including two involving Wales - it's fair to say that the atmosphere being generated inside the Millennium Stadium so far today has reached a whole new level.

A tight game is expected, and if these opening minutes are anything to go by we could be in for a real thriller."

Argentina obviously want to build an early lead, with Pablo Matera trying to smash his way forward, but a heavy hit from Jamie Heaslip stops him in his tracks, and gives Ireland a scrum. Argentina use their power in the pack superbly though, winning a penalty which allows them to get back into Ireland territory. That's just the second scrum Ireland have lost all tournament.

Argentina's impressive start gets better as Cordero chips the ball forward down the right, with Tuculet and Imhoff both giving chase. The duo do just enough to stay onside, before Imhoff reached the ball just in time to ground it right at the back of the in-goal area. The referee take a good look at the replay, but there's nothing wrong with that. It's superb running from Imhoff.

Ireland look absolutely shell-shocked! Creevy quickly forces a turnover to give the ball back to the Argentines, while there could be a further blow for Joe Schmidt's side as Tommy Bowe appears to have injured his leg. He's going to have to go off, with Luke Fitzgerald taking his place.

There's a few minutes delay while Bowe is stretchered off, but once the winger is safely off the pitch, Nicolas Sanchez steps up to take a penalty, after Ireland illegally forced a turnover just prior to Bowe's injury. The fly-half has been having an excellent tournament with the boot, and he maintains his 100% record today, easily chipping it through the posts.

MISSED DROP GOAL! Argentina look just unstoppable as Creevy spots Senatore making a run down the left. He picks up some territory, but is blocked, forcing Argentina to work the ball back into the middle. Ireland do enough to close the gaps, forcing Sanchez to look for the drop goal, but he gets it all wrong, kicking it short and wide.

SIN BIN! Argentina make their first real mistake, as Ramiro Herrera shoulder charges into Keith Earls, earning himself a 10-minute stint in the sin bin. It's a vicious hit, and seems to have left the Ireland centre in quite a bit of pain. It's woken the Irish fans up too, as they know this is their chance to get back into the match.

Here's the latest from Dan Lewis:

"Well so much for the tightly-contested match I - and many others - predicted pre-match. The Irish have been left shocked by this early deficit, but with a man advantage and their supporters still behind them, this one is still far from over."

Ireland finally get some points on the board thanks to a chip shot from Ian Madigan. The fly-half had tried to go in for the try, taking the penalty quickly before sprinting over in between the posts following an offside by Argentina, but the referee wasn't happy with it, and calls him back for an attempt at the posts.

Despite still being a man short, Argentina are on the charge again, with Lobbe and Tuculet both getting touches as the Pumas work the ball back into Irish territory. Chris Henry is penalised for going in from the side on Matera, giving away a penalty, and earning himself a talking to from the referee.

Sanchez's one drop goal miss remains the only blot on his record in this match as he fires another penalty straight through the posts to restore Argentina's 17-point advantage. The television cameras quickly cut to the injured Johnny Sexton in the stands, who has his head buried in his hands.

Ireland have a scrum, and this time both packs hold firm, allowing Conor Murray to get the ball out at the back, but the ball quickly ends up back in Argentine hands, with Juan Imhoff passing to Sanchez, who takes is back across the half-way line. Despite being down to 14, Argentina still look the stronger of the two sides.

MISSED PENALTY! Ireland are penalised for not rolling away, giving Sanchez another shot of the posts. It's a little further out than some of his earlier attempts though, and his kick is kept out by the left post.

It's somewhat against the run of play, but Ireland get themselves back into this match with a stunning run from Luke Fitzgerald. Henshaw creates a bit of width, allowing Tommy Bowe's replacement to cut inside from the left sideline from just inside Argentina territory, taking it all the way for Ireland's first try of the match.

The Irish fans have been kept pretty quiet so far, but the volume is starting to creep up in the Millennium Stadium now. Argentina are back up to 15 though, with Herrera coming to the end of his spell in the sin bin.

Ireland look a much more confident side now as they quickly find themselves back in Argentine territory. Madigan passes to Earls, who tries to smash his way through the middle before passing back to Madigan. The fly-half gives away the scrum when he knocks on though, and appears to have injured himself in the process, but after a quick check over from the medical team he seems ok to continue.

Argentina's first scrum of the match is an untidy one, with the ball coming loose. Dave Kearney tries to pounce on it for Ireland, and does enough to win a put in for Joe Schmidt's side.

MISSED PENALTY! As a result of the second scrum, Ireland win a penalty. It's a tricky angle though, and Madigan's curling effort is kept out by the left post.

Dan Lewis reports from Cardiff:

"Momentum is such a big thing in this sport, and it is very much with Ireland right now. That Madigan pen miss may prove costly, but you feel that there is another try to come before the break."

Both teams are starting to show a few signs of wear and tear. It looked like Dave Kearney was having a finger popped back in by the Irish medical team, while Agustin Creevy is down with an apparent groin injury. After a few moments with an ice pack he's quickly back on his feet though.

Ireland's scrum has been hit and miss in this first half, and it goes wrong again as Cian Healy is penalised for collapsing it, allowing Argentina to boot the ball away for a lineout. Ireland have fought hard to get back into this match, they won't want to concede a third try so close to half time.

Healy quickly makes amends for his error in the scrum, helping force a turnover with a big tackle, before Rory Best was able to pick the ball up for Ireland. Ireland keep the ball following their lineup, but a forward pass from Chris Henry gifts it straight back to the Pumas.

So, after a lightning-fast start from Argentina, Ireland have slowly fought their way back into their Rugby World Cup quarter-final, but it's still the Pumas who hold the advantage at the interval. It will take another determined effort from Ireland if they are to overhaul the 10-point gap between the two sides in the second half.

Defensively, Ireland were woeful in the opening few minutes, allowing Juan Imhoff and Matias Moroni to put a couple of early tries on the board for Argentina. Luke Fitzgerald's try for Ireland was just stunning though, and really got the crowd back behind Ireland as well as getting some much-needed points on the board. The Six Nations champions will need to make a better start to the second half to avoid falling further behind.

Given the scoreline, it's a little surprising to look at the stats from the opening 40 minutes. Ireland had 56% of the possession and 53% of the territory, but Argentina have made almost twice of many attacking metres as their opponents. Leonardo Senatore leads the way so far, with 61 metres made. Fitzgerald was the best of the Ireland players going forward with 43 metres, despite only coming off the bench midway through the half.

Ireland supporters in Millennium are immense. Doing everything to lift the team. #ShoulderToShoulder #IREvARG pic.twitter.com/q12tZySOnB — Irish Rugby (@IrishRugby) October 18, 2015

The players are starting to make their way back out for the second half at the Millennium Stadium. It's going to be a big 40 minutes for both teams.

RESTART! Argentina get the second half underway.

Argentina are clearly looking for a similarly quick start to the first half, with Sanchez and Ayerza working the ball across to Moroni, who opening the scoring in the first half. Ireland have men across to block the centre this time, but Argentina keep the ball moving, until Cordero loses out to Chris Henry.

Ian Madigan has picked up a cut above his right eye following an accidental clash of heads with one of his teammates, it doesn't look to be bleeding too heavily though.

Dan Lewis reports at the start of this second half:

"Could this be a half where record are broken? All the stats suggest that Ireland face the impossible task over these next 40 minutes, but three sides have previously battled back from 10 down at the interval. An early try will lift the roof off this stadium."

It's yet another brilliant move from Luke Fitzgerald, as the replacement winger slips past Agustin Creevy before passing to Jordi Murphy, leaving the flanker to power over. With the extras from Madigan, Ireland are just a penalty back now, having been 17-0 down midway through the first half. That's just the start Ireland needed after the break.

Ireland have a scrum, which was patchy in the first half, but this time is holds firm, resulting in Argentina giving away a penalty. It's kicked for a lineout at the 22, which Best launches deep to find Murphy. He gets the ball to Heaslip, who passes out wide to Henshaw. This is another dangerous looking move from Ireland, who are starting to hit their stride.

Argentina try to respond, with Cordero offloading the ball to Imhoff. The winger weaves around, dodging several tackles before eventually running out of options. Ireland looked like their were going to score their third try a moment ago, but are now on the back foot again.

Argentina can't get the try, but they do enough to force a penalty after Imhoff is tackled, allowing Sanchez to add his third penalty of the game. Ireland were dominant in the second half against France last week, while Les Bleus struggled to get going, but it looks like Argentina are going to put up more resistance in the second 40 minutes.

Ramiro Herrera is a lucky, lucky boy! The prop has already had a 10-minute spell in the sin bin, and appears to lead with his head in the ruck again. A second yellow card would see him heading off again, and not returning, but the referee thinks that there was just enough of his left arm involved to give him one more chance. Expect to see Argentina taking him off shortly, if only to ensure they don't go down to 14 again.

Herrera gets to stay on the pitch, but he does give Ireland another penalty, which Madigan calmly fires through, cutting to gap to three points again. This has become more like the tight contest that many expected ahead of kickoff since the restart.

There's an important change for Argentina as captain Agustin Creevy is heading off, with Julian Montoya taking over at hooker. Argentina are back on the ball as well, forcing a scrum, but Cordero is unable to make the most of it, before Ayerza gives away a penalty trying to win the ball back, diving through on Conor Murray.

The referee and TMO take a good look at the Marcos Ayerza tackle. He never got his hands to the ball, but they're happy enough for him to remain on the pitch.

MISSED PENALTY! Ian Madigan has another look at the posts, with a chance to level up the scores for the first time since Moroni's opening try. It's a long way out though, and he drags his shot just wide.

Dan Lewis provides an update from the Millennium Stadium:

"I don't think it would be an exaggeration to suggest that these next 10 minutes will decide the outcome of this game. It is very balanced right now - as balanced as it has been all afternoon - and the next score could make all the difference."

Argentina have been enjoying a good spell of possession over the last couple of minutes, with Tomas Cubelli and Sanchez taking the ball into the Ireland 22, before Devin Toner, the tallest player in the tournament, is penalised for a high tackle on the fly-half.

Nicolas Sanchez makes is six successful kicks from seven attempts at the posts today to put Argentina six points ahead, while also making himself the top points scorer at this year's Rugby World Cup so far. Argentina are starting to show signs of fatigue, struggling to get the ball out wide, but as long as Sanchez is kicking like that, they're going to make it difficult for Ireland to get back on level terms.

Jordi Murphy and Jack McGrath play their way through the middle before Madigan, who still has some blood coming from his eyebrow, kicks it deep down field. Argentina have the lineout, but they'll need to make sure they don't give it back to Ireland so close to their own try line.

That's surely now one foot in the semi-finals for Argentina, as full-back Joaquin Tuculet uses every inch of his body to stretch the ball over in the corner, just keeping enough of his hand on it to ground the ball. Rob Kearney tried to close the gap down, but the Argentine full-back had too much pace.

With Sanchez adding the conversion, Ireland realistically need two tries in the final 10 minutes, but it's Argentina on the attack again, with the fresh legs of Jeronimo de la Fuente, who came on just before Tuculet's try, skipping down the right before eventually being caught by Chris Henry.

Robbie Henshaw breaks down the right, trying to give Ireland some hope of coming from behind in the final moments of this match. He passes to Dave Kearney, but there are no option except to kick for the winger.

Juan Imhoff hammers the final nail in Ireland's coffin after picking up an offload from Fernandez Lobbe, leaving him with nothing but space ahead of him after escaping a diving tackle from Dave Kearney. He sprints over for Argentina's fourth try of the match.

Dan Lewis reports from the Millennium Stadium:

"Well that should be that. Phenomenal showing from Argentina, who are showing the type of spirit that took then so far eight years ago. The Millennium Stadium will be left with just blue and white shirts shortly, as the Irish make their way for the exits. Heartbreaking."

Keith Earls goes in a bit late on Cordero, giving Sanchez, who has just been named as the man of the match in the stadium, another chance to kick, and he just squeezed it inside the left upright.

The crowd is almost silent, but for small pockets of Argentina supporters. As the match heads into the final minute, Argentina still have possession, but Ireland win it back. Toner is looking to add a late consolation try, but is floored by Lavanini.

Ireland's wait for a first Rugby World Cup semi-final goes on, as they fall at the quarter-final stage for a sixth time. The scoreline might flatter Argentina a little in the end, but they really were dominant in the first half, and made the most of their chances late on to put the win beyond doubt.

Next up for the Pumas will be the winner of the match between Australia and Scotland, which gets underway at Twickenham in around an hour. We'll be starting our live coverage of that match in the next few minutes, so make sure you stick around to see who claims the final place in the last four.

Right, that's all from this match, but don't forget to catch up on all the latest from the Rugby World Cup on our dedicated page for the tournament. Thanks for joining me this afternoon. Goodbye.