Argentina piled more World Cup misery on Ireland by reaching the last four of the competition with a 43-20 victory in Cardiff.

Ireland's record of never having reached the semifinal of a World Cup continued as Argentina scored four tries through Juan Imhoff (2), Matias Moroni and Joaquin Tuculet.

Ireland battled back from a first-quarter deficit of 17-0 with tries from Luke Fitzgerald and Jordi Murphy making it a three-point game at one stage, but the Pumas powered away in the closing stages to repeat their 1999 and 2007 World Cup victories over the Irish.

Ireland turned to Ian Madigan after outside-half Jonny Sexton was ruled out. Sexton was originally named by Ireland, but he pulled out with a persistent groin problem on Saturday morning to add to their woes. Key pack performers Paul O'Connell, Peter O'Mahony and Sean O'Brien were all missing and Chris Henry, Jordi Murphy and Iain Henderson came into the side following their 24-9 pool victory over France last weekend.

Argentina restored 10 players after their straightforward victory against Namibia and only the suspended Marcelo Bosch was missing from a full-strength Pumas side.

Ireland were featuring in their sixth World Cup quarterfinal having not won any of the previous five while Argentina were chasing a second semifinal after making the last four in 2007.

Argentina had not beaten Ireland since a pool game in that tournament, with the men in green winning the five matches between the two countries since.

Ireland started as favourites but the absence of injured trio Sexton, O'Connell and O'Mahony as well as the suspended O'Brien gave Argentina belief that they would be able to bridge the gap.

And they started in spectacular fashion with a third-minute try as fullback Joaquin Tuculet took a battle and flanker Pablo Matera made hard yards down the middle.

The ball went quickly through the hands of Nicolas Sanchez, Juan Martin Fernandez Lobbe and Santiago Cordero for Bosch's replacement Matias Moroni to make the corner, Sanchez converting for a seven-point lead.

Ireland were shell-shocked but worse was to come after 10 minutes when another free-flowing move ended with Cordero's kick exposing the Irish cover.

It was touch and go whether wing Juan Imhoff would reach the ball in time to ground it, but replays showed he did so brilliantly and Sanchez added the extras with a kick off the upright.

Ireland's injury curse struck again when Tommy Bowe left the field on a cart and Sanchez extended Argentina's lead to 17 points with a well-struck penalty.

But Argentina's momentum was slowed by the sin-binning of prop Ramiro Herrera for a late tackle on Keith Earls and Madigan finally put Ireland points on the scoreboard with a straightforward penalty.

However, Argentina restored their 17-point advantage when Ireland flanker Henry was penalised for entering the wrong side of a ruck and Sanchez's trusty boot did the rest.

Sanchez struck the post with another long-range attempt and Ireland made the most of their good fortune to counter from deep and Robbie Henshaw freed replacement wing Luke Fitzgerald into space. Fitzgerald still had plenty of work to do but he raced inside Tuculet for a try which Madigan converted.

Ireland were belatedly finding some rhythm and Madigan's penalty hit the post - the third time an upright had been struck -- while the Pumas escaped when Sanchez had the ball ripped from his grasp in trying to relieve the pressure.

Argentina needed to regain their composure and they did so to hold Ireland at bay for the rest of an exciting first period.

The next score was crucial and Ireland almost raised the Millennium Stadium roof within four minutes of the restart when Fitzgerald made the most of quick lineout ball off the top.

Fitzgerald burst through some half-hearted Pumas tackling and off-loaded to Jordi Murphy, who charged over for a try which sent the Irish majority in the Cardiff crowd wild.

Madigan's conversion reduced it to a three-point game and they pummelled the Argentina line again, only for the Pumas defence to hold firm this time.

Argentina managed to find some breathing space and Imhoff's burst set up good field position, which allowed Sanchez to land a penalty and extend the gap to 23-17.

But Herrera's indiscipline caught up with him again at a ruck and Madigan was on target to leave the game on a knife-edge.

Ireland were applying pressure at the scrum as the contest headed towards its final quarter, but Madigan failed to take an opportunity to level the scores with a kick from just inside the Argentina half.

Argentina were appearing rattled but they enjoyed some territory and Devon Toner was penalised for a high tackle on Sanchez, which the outside-half made the most of to add another three points.

Both sides were making errors with so much at stake but Argentina were keeping Ireland at arms length and making sure the game was being played in their opponents' half.

They looked to have had a penalty for a scrum infringement but Cordero broke into the Ireland 22 down the right.

The ball was recycled from right to left and Argentina had an extra man over, but Tuculet went for the gap and the television match official confirmed that the full-back had applied downward pressure before losing the ball.

Sanchez converted for a 33-20 lead and Imhoff powered through for his second try of the game, and his fifth of the tournament, to put the issue beyond doubt eight minutes from time.

The outside-half took his final total to 23 with his fourth conversion and fifth penalty of the game as Argentina eased into a semifinal date with either Australia or Scotland.