The way the Irish coach told it during the week, this tour represents two-thirds of his side's World Cup warmup program. It appeared to have escaped the attention of most that Ireland's 30-man World Cup squad has to be named between August's friendlies against Italy and Scotland, and you can take it as read that if you don't show yourself over the next two Saturdays in Argentina, you won't be invited back to Ravenhill in August to get your World Cup passport stamped. It's as simple as that.

Even though Argentina are as understrength as Ireland heading into the two tests, you can't help fell sorry for some of the participants of this tour that their play for a World Cup place takes place on such hostile territory. Over the past four summers on home turf (or winter as it is there), the Pumas have beaten France twice, Wales three times and have pushed both New Zealand and South Africa to within a couple of points. In many ways, a trip to Australia or New Zealand might have been preferable for Ireland's inexperienced tourists. Although they would have faced an increased quality of opposition in either place, nobody would really have expected a below strength Irish team to record a test victory. In Argentina, however, they'll be expected to record a victory in at least one of the tests, all this despite the fact that Ireland have only won one test over there in five attempts down the years. On paper, the second test in Buenos Aires looks the better bet for that needed victory, if only because Ireland's Heineken Cup finalists . . . Geordan Murphy, Leo Cullen, Shane Jennings, Peter Bracken and Eoin Reddan . . . are all likely to start that particular game.

The first encounter in Santa Fe, then, will feature the other 25 tourists, many of whom need a big game to force their way back into O'Sullivan's plans.

To the front-row first, a place not likely to be much fun in a place like Argentina.

In the propping department, Simon Best and Bryan Young will start the first test at Club Atletico Colon in Santa Fe, with Peter Bracken likely to replace the tight-head for the second test the following weekend. He certainly deserves the opportunity.

While Jerry Flannery is certain of a World Cup spot, the Munster hooker could conceivably leap-frog Rory Best as Ireland's starting hooker if he can be as accurate out of touch and dynamic in the loose in Argentina as he was last season. Expect him to start both tests, with Frankie Sheahan and Bernard Jackman rotating on the bench.

In the second-row Malcolm O'Kelly, who's likely to start the first test alongside Mick O'Driscoll, really needs to put in a big performance. Since missing the Six Nations with a recurring knee injury, Ireland's most-capped player has been well below form in a Leinster shirt and if he doesn't get his act together in the next two weeks, you could see him missing out on the World Cup altogether. It's likely that O'Sullivan will pair next season's likely Leinster combination of Trevor Hogan and Leo Cullen together for the second test, giving all his second-rows a decent bite of the action.

The back-row, as always, will be hugely competitive.

Alan Quinlan, who should start in the number six shirt in the first test, can certainly make the World Cup cut if he plays as imposingly as he has in recent weeks, but it's likely that all six back-rows in the squad will get reasonably equal game-time over the next fortnight. Keith Gleeson and Stephen Ferris, you feel, will need to produce something extraordinarily special in Argentina to make the World Cup squad, while Neil Best and Shane Jennings are by no mean certainties to be in France come September. In fact, the only member of the back-row in Argentina guaranteed a World Cup spot is Jamie Heaslip, if only because he's the only other true number eight in the Irish mix.

At half-back, meanwhile, Isaac Boss and Paddy Wallace will start in Santa Fe, giving both an opportunity to nail down their respective places as Peter Stringer and Ronan O'Gara's shadows, but expect Eoin Reddan to have something to say about that in the second test, and possibly Jeremy Staunton too, if the Wasps out-half does get the nod to go to Argentina after last night's Churchill Cup game against Canada.

In the centre, it's going to be a big tour for Andrew Trimble, who can prove to O'Sullivan once and for all that he's a much better option at centre than Shane Horgan, while Kieran Lewis and Barry Murphy can be expected to start one test each beside him over the next fortnight. As for the six outside backs in the squad, they all should, with the possible exception of Luke Fitzgerald, start at least one game on tour and it will be particularly interesting to see how Brian Carney fares if he's plunged into his first game of international rugby. The pity for these players, Geordan Murphy excepted, is that only a truly mind-blowing performance will put them in the World Cup picture.

Most of Ireland's back slots are virtually set in stone for the tournament and O'Sullivan is not the type of coach to change his mind.

TEST DETAILS

FIRST TEST ARGENTINA v IRELAND
Santa Fe, 26 May, 2010 (GMT) Possible team: G Duffy; R Kearney, K Lewis, A Trimble, T Bowe; P Wallace, I Boss; S Best (c), J Flannery, B Young; M O'Driscoll, M O'Kelly; A Quinlan, K Gleeson, J Heaslip

SECOND TEST ARGENTINA v IRELAND
Buenos Aires, 2 June, 2010 (GMT) Possible team: G Murphy; B Carney, B Murphy, A Trimble, T Bowe; P Wallace, I Boss; S Best (c), J Flannery, P Bracken; T Hogan, L Cullen; N Best, S Jennings, J Heaslip