Ronan O'Gara is confident Ireland have received a "kick on the backside" at the perfect time and backed Joe Schmidt's men to raise their game significantly against France next Sunday.
Irish optimism has been dampened after a laboured win over Italy on Sunday, despite the 16-9 victory being enough to book a place in the last eight, but O'Gara believes his country will step it up in next weekend's pool decider.
Speaking to RTÉ Sport, O'Gara said: “It’s 80 minutes, that’s all that matters. All the preparation is done during the week, but in the 80 minutes different events occur.
"This set of circumstances against the French will be completely different. Ireland will have a fear factor on Sunday. I think with all respect to Italy, they wouldn’t have had that [against them].
"When you play Canada and Georgia you can maybe feel a little bit surreal about your game in aspects but [against France] it will come hard and it will come fast.
"France will be bigger men than they’ve faced in the competition before so it will be a real test on Sunday but one I’m confident they’ll pass. They got a small kick on the backside yesterday and that’s perfect timing."
After seeing off Canada 50-7 and Romania 44-10 in their opening two Pool D games there was a wave of optimism surround Ireland's hopes at this World Cup, but O'Gara warned the bar has been raised by other performances in England so far.
"Anyone who saw the Australia-England game would realise how good Australia were so that set a new level in people’s minds about the level Ireland have to reach," he said.
"Ireland have been going really well, they’ve been extremely consistent over the last 24 months but I think to win the World Cup they have to be excelling. Against Italy they didn’t do that but they didn’t need to do that.
"It’s been really a case of delivering on the day what’s needed and Ireland have been extremely difficult to beat. It was never a case yesterday in the ground that you felt Italy were going to win the game. The [French] media and people in French rugby are frustrated."
One place Ireland will enjoy an advantage over the French will be in the stands, with the Irish enjoying incredible support in the tournament across the water.
O'Gara, a coach at Racing 92, claimed the feverish interest the Irish have in the national team's World Cup hopes is not replicated in France.
"In Ireland we’re hugely patriotic and there’s massive support for the Irish team. The club players in France get on with their team, be it Clermont or Racing or Stade, but the actual interest in the national team just wouldn’t be the same.”
