Kevin Maggs carries it forward. (Getty Images)

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Ireland marched proudly into the World Cup quarter-finals and banished the ghosts of 1999 as they beat Argentina 16-15 in a thrilling match in Adelaide.

The result sets up a decisive Pool A match against Australia, with the winner taking the top spot and the loser likely to face France in the knockout phase.

Alan Quinlan scored the only try of the match - while Ronan O'Gara scored two penalties as a second-half substitute, and David Humphreys kicked a penalty and a conversion.

O'Gara's arrival in the match on the hour proved a crucial moment as the Munsterman provided a more effective option at fly-half and the Ireland back line began to spark into life.

The first half was an intense affair, Argentina dominating but failing to finish off their opportunities and blowing three clear chances to cross the Irish line.

Their first came just after the 20-minute mark when a move to their left wing was intercepted by Shane Horgan, while two more openings were spoiled by poor execution as a pass floated out of touch and then supporting players infringed with the goal-line beckoning.

The Argentinian pack was in impressive form, rolling Ireland back with an ease which would have worried coach Eddie O'Sullivan.

But he would have been delighted with the positioning of Quinlan, normally a blindside flanker who started as a makeshift opensider, as he popped up in an excellent position to take a pass from Keith Wood and power over the line just on the 20-minute mark to open Ireland's account.

Sadly for the flanker he rolled on to his shoulder in the tackle as he went over the line and left with a suspected dislocation of the joint.

Argentina then mounted pressure on the Ireland line, with their three chances all going begging and Gonzalo Quesada's drop goal and penalty the only reward going into the break a point down.

Just after half-time Quesada kicked another penalty - and when Ignacio Corleto kicked a long drop goal just before the hour mark he put his side ahead deservedly.

O'Sullivan reacted by replacing Humphreys with O'Gara, and the effect was immediate.

He kicked a penalty, and suddenly the Ireland back line was slicing forward and putting Argentina under more pressure.

His second penalty three minutes later put Ireland back in front - and although Corleto's drop goal eight minutes from time set up a thrilling finish, the men in green had enough resilience to survive.

Girvan Dempsey provided the final moment of excitement as he effected a perfect tackle on Diego Albanese as the elusive winger threatened to destroy Irish dreams as he did four years ago.

Albanese was dumped over the touchline - and when referee Andre Watson blew for full-time the crowd, fiercely partisan in favour of Ireland, erupted in delight.

Teams

Argentina: Corleto, Nunez Piossek, Orengo, F. Contepomi, Albanese, Quesada, Pichot, Grau, Mendez, Reggiardo, Fernandez Lobbe, Alvarez, Ostiglia, Martin, Longo Elia.

Replacements: Scelzo for Reggiardo (73).

Not Used: Ledesma, Albacete, Phelan, N. Fernandez Miranda, Gaitan, Martin Hernandez.

Pens: Quesada 3.

Drop Goals: Quesada, Corleto.

Ireland: Dempsey, S. Horgan, O'Driscoll, Maggs, Hickie, Humphreys, Stringer, Corrigan, Wood, Hayes, O'Kelly, O'Connell, S. Easterby, Quinlan, Costello.

Replacements: O'Gara for Humphreys (56), Horan for Corrigan (56), Miller for Quinlan (20).

Not Used: Byrne, O'Callaghan, G. Easterby, Kelly.

Tries: Quinlan.

Cons: Humphreys.

Pens: Humphreys, O'Gara 2.

Att: 33,000

Ref: Andre Watson (South Africa).