Paul O'Connell today described Ireland's bid to keep their World Cup hopes alive as one of the biggest tests of his international career.
Ireland need to defeat pool D leaders Argentina and score four tries while denying their opponents a bonus point in defeat if they are to reach the quarter-finals.
Argentina have yet to concede a try in the tournament and look one of the form teams in France.
O'Connell however believes it is far from a mission impossible for Eddie O'Sullivan's side.
"It is a massive challenge but I think we just have to concentrate on beating them and if we win the game, something might come out of it," said O'Connell.
"Something might click. If we just concentrate on winning the game we will see if something happens after that.
"We are disappointed we are in this situation but we have to make do with what we have got. We need to put Argentina under pressure and trying to put phases together."
Meanwhile, Rory Best looks set to make a sensational return.
The Ulster hooker, who missed the 25-3 defeat to France having dislocated his thumb in the victory over Georgia, will find out in the next 24 hours whether he will take his place in the line-up to face Los Pumas.
The initial prognosis ruled Best out of the final two pool games, with Jerry Flannery taking his place against the French in Paris.
But the 25-year-old's progress has been ahead of schedule. He took part in training at the Stade Bordelais yesterday morning and Ireland coach Eddie O'Sullivan yesterday gave him an extra 24 hours to prove his fitness, leaving the hooker's berth vacant when he announced his line-up.
Having undergone intensive physio work yesterday, he is expected to be fit.
"Rory has almost recovered from his injury and we will know in the next 24 hours if he is available," said O'Sullivan last night.
" He is pretty close actually. The medical team have performed a bit of a miracle there."
Geordan Murphy and Denis Hickie have been brought back from the cold for the crunch clash.