Ireland coach Joe Schmidt is urging several players to stake a claim for places ahead of the first of two Tests against Argentina.
Schmidt has made it clear to his players that Saturday may be their only opportunity.
South African Robbie Diack will make his Ireland debut in a back row where Jordi Murphy starts his first game for Ireland when winning his third cap.
As expected, Darren Cave has been handed the number 13 shirt and will line up with Ulster team-mate Luke Marshall in a backline where Simon Zebo returns to the international scene.
Connacht pair Kieran Marmion and Rodney Ah You are poised to make their Irish debuts off the bench.
Schmidt said: "It's a great opportunity and it's a real responsibility. If the opportunity is afforded to you then I think you've got to reciprocate with the best performance you can put together.
"The way they've trained this week that's certainly what they are working towards with the combinations we have, with the combative nature of the way the Argentinians play.
"They are a little bit unknown, they are a little bit harder to predict than other teams we have played.
"Then to be able to react and endure what will be a pretty tough Test match in a very tough environment, it's going to give us a bit more information about how these guys will cope in the future. "
The Ireland coach is able to experiment with the Pumas not at full strength - but Schmidt believes the same option may not be open to him in November.
He continue: "We have this one window to really do that. The Guinness Series is going to be measurably tougher with South Africa and Australia.
"It's going to be very, very tough here but one of the things that you want to find out is how the players cope in a tough environment.
"It will be hostile, it's a place where Test match rugby hasn't been before so the local population will be very much behind the Argentinians.
"It's a pitch that's a different size and it's the first time this combination has been put together for Ireland.
"So there are a number of challenges. We just want to really see how they manage the situation."
Ireland team to face Argentina in First Test at Resistencia on Saturday:
F Jones (Munster), A Trimble (Ulster), D Cave (Ulster), L Marshall (Ulster), S Zebo (Munster), J Sexton (Racing Metro), C Murray (Munster), J McGrath (Leinster), R Best (Ulster), M Ross (Leinster), I Henderson (Ulster), P O'Connell (Munster), R Diack (Ulster), C Henry (Ulster), J Murphy (Leinster).
Replacements: D Varley (Munster), D Kilcoyne (Munster), Rodney Ah You (Connacht), D Toner (Leinster), J Heaslip (Leinster), K Marmion (Connacht), I Madigan (Leinster), F McFadden (Leinster).