Argentina were on the cusp of a hard-fought opening Pool C triumph before Quinlan - making his U-20 debut as a 78th-minute replacement - came to Ireland's rescue by landing a hugely difficult penalty from close to the right touchline.

Irish captain Nick McCarthy said he was thankful that "the kickers took their chances very well" in the Parma heat, as Joey Carbery fired over five penalties from six attempts and his replacement Quinlan split the posts decisively right at the death.

However, Nigel Carolan and his management team will be disappointed with the try-scoring opportunities that Ireland failed to convert, including a Stephen Fitzgerald first half effort that was ruled out for a forward pass from Carbery.

Ireland's matchday squad included six players who saw action in last year's tournament in New Zealand.

It would have been eight had Ross Byrne not suffered a Championship-ending back injury and Ciaran Gaffney was a late withdrawal from the team today with an ankle injury.

Carbery, who took over the out-half reins from Byrne, nailed a nerve-settling fourth-minute penalty after Argentina were guilty of not rolling away, but winger Fitzgerald had a clearance kick charged down from the restart and a subsequent penalty allowed Domingo Miotti to draw los Pumitas level.

In humid conditions at Stadio Sergio Lanfranchi, a Garry Ringrose turnover gave Jacob Stockdale a chance to stretch his legs on the right wing, while Carbery's pinpoint cross-field kick was brilliantly claimed by Fitzgerald on the left.

Unfortunately, the supporting Josh Murphy was unable to hold onto his pass with the try-line in sight.

Powerful running from Ulster duo Lorcan Dow and Sam Arnold gave Ireland a good platform, however both sides had set piece issues to iron out in a mostly stop-start first quarter.

With Ringrose leading the midfield threat, Ireland missed out on another try-scoring opportunity when Emiliano Boffelli tackled Stockdale into touch after crisp passing from Arnold and Billy Dardis had opened up some space for the Ulsterman.

Fitzgerald succeeded in crossing the whitewash in the 24th minute, but Carbery's final pass was ruled forward by referee Lloyd Linton.

It was a disappointing outcome to an attack that had showcased some fine instinctive running from Stockdale and Carbery.

The scrum was an area of concern for Ireland, though, with one going against the head and Argentina then forcing a penalty at a set piece in their 22.

On the half hour mark, a ground-gaining Argentinian maul set up a 40-metre drop goal effort from Miotti which he took with aplomb for a 6-3 lead.

The Pumitas out-half was just short with a monster penalty attempt before Carbery, growing in influence in open play, equalised with a very well-struck penalty from the 10-metre line.

The UCD clubman then nudged Ireland in front - 9-6 - in first half injury-time when punishing an overeager Argentinian scrum.

Argentina managed to respond within three minutes of the second period, captain Bautista Ezcurra making the initial break before replacement Portillo shrugged off Carbery's tackle to crash over in the right corner for the game's only try.

Miotti continued his impressive kicking form with a terrific conversion.

Carbery recovered his poise with a nice break over halfway and then knocked over his fourth successful penalty, making it a one-point game with the Irish pack notably improving their set piece return.

Ireland made further headway as hooker Zack McCall went close to scoring after breaking off a maul, but a double tackle managed to dislodge the ball from Arnold's grasp as the Ulster-capped centre had a cut at a line.

After Carbery landed his fifth three-pointer of the day, Miotti pushed a left-sided penalty attempt wide and a couple of handling errors from Argentina allowed Ireland to claw back some hard-earned territory.

Into the final quarter, Ireland chipped away at the Argentinian defence with front row replacement Sean McNulty and Conan O'Donnell helping them to make the hard yards.

The direct route, allied to slick hands from Ringrose, led to Fitzgerald threatening from a kick through but Argentina did well to scramble back and avert the danger.

Carbery suffered his only penalty miss soon after and Argentina built for a strong finish, replacement scrum half Patricio Baronio threatening on a midfield run and then winning turnover possession at the back of an Irish scrum.

His opposite number, Irish debutant Charlie Rock, combined with Carbery to prevent an Argentinian try under the posts.

However, a subsequent offside allowed full-back Boffelli to clip over a right-sided penalty and suddenly, los Pumitos were only two minutes from victory.

Composed carrying from Stockdale and Ringrose, coupled with good clearing out from the forwards, saw Ireland probe for openings past the 10-metre line.

They earned a final penalty for Argentina going off their feet and with seconds remaining, the left-footed Quinlan was called upon to go for goal.

The Cork Constitution clubman more than stood up to the task, curling over a memorable strike to spark Irish celebrations and break Argentinian hearts.

Scorers:

Ireland: Pens: Joey Carbery 5, Tomás Quinlan

Argentina: Try: Santiago Portillo; Con: Domingo Miotti; Pens: Domingo Miotti, Emiliano Boffelli; Drop: Domingo Miotti

IRELAND U-20: Billy Dardis (UCD/Leinster); Jacob Stockdale (Queen's University Belfast/Ulster), Garry Ringrose (UCD/Leinster), Sam Arnold (Ballynahinch/Ulster), Stephen Fitzgerald (Shannon/Munster); Joey Carbery (UCD/Leinster), Nick McCarthy (UCD/Leinster) (capt); Jeremy Loughman (UCD/Leinster), Zack McCall (Queen's University Belfast/Ulster), Oisin Heffernan (Terenure College/Leinster), David O'Connor (St. Mary's College/Leinster), Alex Thompson (Queen's University Belfast/Ulster), Josh Murphy (UCD/Leinster), Rory Moloney (Buccaneers/Connacht), Lorcan Dow (Queen's University Belfast/Ulster).

Replacements used: Andrew Porter (UCD/Leinster) for Loughman (8 mins), Sean McNulty (UCD/Leinster) for McCall, Conan O'Donnell (Sligo/NUIG/Connacht) for Heffernan, Jack Dwan (UCD/Leinster) for Thompson, Nick Timoney (St. Mary's College/Leinster) for Moloney (all 63), Charlie Rock (Old Bevedere/Leinster) for McCarthy (71), Fergal Cleary (Lansdowne/Leinster) for Arnold, Tomás Quinlan (Cork Constitution/Munster) for Carbery (both 78).

ARGENTINA U-20: Emiliano Boffelli (Duendes RC/Rosario); Eugenio Achilli (Urú Curé/Cordobesa), Tomás Granella (Liceo RC/Cuyo), Bautista Ezcurra (Hindú Club/URBA) (capt), Santiago Resino (Universitario/Tucumán); Domingo Miotti (Tucumán Lawn Tennis/Tucumán), Lautaro Bazán Vélez (Córdoba Athletic/Cordobesa); Javier Díaz (Natación y Gimnasia/Tucumán), Ignacio Calles (Liceo Naval/URBA), Cristian Bartoloni (Pucará/URBA), Vittorio Rosti (Duendes RC/Rosario), Ignacio Larrague (CASI/URBA), José Deheza (Jockey Club/Cordobesa), Lucas Gasparri (Sporting/Mar del Plata), Ernesto Olmedo (La Tablada/Cordobesa).

Replacements used: Santiago Portillo (Los Tarcos/Tucumán) for Olmedo (12-15 mins), Portillo for Olmedo, Eduardo Bello (Atlético del Rosario/URBA) for Bartoloni (both half-time), Nicolás Ocello (Olivos RC/URBA) for Díaz, Ignacio Calas (La Tablada/Cordobesa) for Deheza (both 51), Juan Cruz Mallía (Jockey Club/Cordobesa) for Achilli (58), Patricio Baronio (Jockey Club/Rosario) for Bazán Vélez (63), Ignacio Albornoz (Tucumán RC/Tucumán) for Miotti, Gaspar Baldunciel (Asociación Alumni/URBA) for Calles (both 66).

Referee: Lloyd Linton (Scotland)