Sportal.co.nz 09.Mar.2013Getty Images
Two teams that were expected to challenge for the title before the tournament began instead find themselves locked in a desperate struggle to avoid the wooden spoon.
It has been 15 years since Ireland finished bottom of the table, but that is the fate that may await them in Rome tomorrow week if they fail to topple winless France.
History is stacked against them, though, as they have only bettered Les Bleus once in 13 meetings spanning a decade.
A self-destructive streak, combined with an awful injury list, has seen a Six Nations that exploded into life in Cardiff five weeks ago unravel alarmingly, moving O'Brien to demand an end to their recent malaise.
"We know what we have to do against France - losing is not an option," the Lions back-row contender said.
"There is a pride element and we're playing at home. If we win the last two games we leave ourselves in a good enough place, hopefully. That starts this weekend.
"We need to come out of the traps nice and hard. After the disappointment of losing to England and Scotland, everyone's up for it.
"I don't care about how France have been doing or where they finish up, it's about us, this team and this squad.
"All I'm worried about is making sure we're in the right place this weekend."
Ireland have previously displayed the capacity - most recently against England in 2011 and Australia later that same year - to deliver an outstanding performance and victory when the outlook is at its bleakest.
Their inconsistency has been maddening and looks set to deny head coach Declan Kidney a contract extension beyond the summer, but even allowing for their depletion by injury they remain dangerous adversaries.
O'Brien has called for a display of controlled ferocity, mindful that too much emotion will prove counter-productive.
"To win any international you have to beat up the opposition," he said.
"Physically we'll have to go to that place where it's manic and they don't know what's coming at them.
"Both teams need to win, but if you're desperate you can do some silly things.
"It's about having a clear mind and being aware of the circumstances you're in at any given time."
Adding to Ireland's frustration is that against England their tactics and execution were poor while in Edinburgh they were left wondering how they failed to turn 79 per cent possession into victory.
Had they been smarter in Dublin four weeks ago and shown greater composure at Murrayfield, they and not England would have been two victories away from a Grand Slam.
"We're created so much and aren't that far away from it. A ball here and there and it would have been different. It's about knowing how to finish," O'Brien said.
"That are more positives than negatives. Although results haven't gone our way we are creating chances. We need to show more composure."