The stakes are high for Pool C's most eagerly-awaited encounter between the tournament's youngest squad - the Wallabies - and its oldest, with the winner securing sight of the quarter-finals.
Tri-Nations champions Australian start as heavy favourites with the rivals' contrasting recent records pointing to a comfortable Wallaby win.
Offering an honest appraisal of Ireland's form, O'Connell accepts that expectations the World Cup's second favourites will be humbled in Auckland this week are understandably low.
But the Lions captain is convinced his team is capable of taming the Wallabies - if they approach the match with the right mentality.
"There's no denying Australia are the form side compared to us. For us to win the game we will need a massive performance," he said.
"Any motivation we can get we'll use. There's no doubt Irish teams are better when their emotion and passion are high.
"Hopefully that will be there in abundance against Australia. On form they're a long way ahead of us at the moment.
"We've failed to produce our best in the last five games and there's no doubt we're the underdogs.
"We're used to that and we can't have any qualms about it.
"We've failed to produce the goods for five games in a row now, but hopefully it happens on Saturday.
"I look at the quality of the players and experience we have and I think absolutely there's a big performance in us.
"We've been playing way under our potential."
Irish hopes are pinned on their ability to reproduce the perfect storm that denied England the Grand Slam in March.
It was a brutal performance that was close to perfection, but O'Connell concedes it has proved a one-off in a year plagued by inconsistency.
"Similarly to now when we haven't performed to our ability for the last five games, week after week we failed to reach our potential in the Six Nations," he said.
"We played for 20 minutes here and there, 30 minutes here and there. We showed only flashes of what we can do.
"We're failing to produce it for 80 minutes but against England we managed that.
"When we can do that, which is what good teams do, we are an excellent side that can compete with anyone.
"That's what we must do against Australia - be an 80-minute team."
Ireland have fielded their strongest possible 22 to meet the Wallabies.
Full-back Rob Kearney, prop Cian Healy and flanker Sean O'Brien have returned from injury lay-offs, while the more experienced Eoin Reddan has been preferred ahead of Conor Murray.
The key figure is wrecking ball European player of the year O'Brien, the team's outstanding performer since the start of the Six Nations.
Selected at seven after David Wallace was ruled out of the World Cup with a knee injury, he must either attempt to make some impression on brilliant Wallaby openside David Pocock.
If Ireland revisit their heroics against England, they will be able to match Australia blow for blow.
It is an enormous occasion for many members of the squad with the likes of the aging O'Connell, Brian O'Driscoll and Gordon D'Arcy unlikely to feature in many more big matches.
"It's a massive game for Ireland. It has monumental importance in the pool and will be a really tough game," said O'Connell.
"Australia are playing some great rugby at them moment.
"Australia finished the Six Nations very strong. They were also incredibly patient against and took the opportunities when they came.
"They played cleverly against Italy on the weekend. They were patient and broke them down.
"When they got their opportunities they took them very well."
Many of Ireland's big names have been off-colour during the build up to the World Cup and in last Sunday's unconvincing 22-10 victory over the United States.
D'Arcy and O'Driscoll, both finding their way back from injury, need big performances, as does Jamie Heaslip who has fallen short of the world class form he displayed last autumn.
Jonathan Sexton, retained at fly-half ahead of Ronan O'Gara, also needs to produce after failing to impress against the USA.
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