Defeat at Otago Stadium on Sunday would see the Irish return home without reaching the knockout stages, a heartbreaking conclusion to a campaign that has promised so much.
Just two weeks ago they routed Australia 15-6 in a result that stunned the World Cup and separated the Six Nations and Tri-Nations teams into opposite sides of the quarter-final draw.
Toppling the Wallabies may have issued a reminder that Ireland capable of beating anyone, but O'Driscoll insists Italy were always the gatekeepers to the last eight.
"It's win or bust. We always felt as though it would be a very important fixture," he said.
"We felt as though we had the ability to beat Australia, but winning that game hasn't made this group any different. We still have to beat Italy on the final day.
"We realise the magnitude of the match and look forward to that element of pressure.
"We're more relaxed in our own skin knowing that we're capable of that performance against Australia.
"It's about trying to improve on that. We'll be in a good place if we manage that."
Ireland have amassed a 15-match winning streak against Italy yet their hair-raising 13-11 triumph in Rome in February demonstrated that victory must not be taken for granted.
"They've become harder and harder to play in each match over the last four or five years," said O'Driscoll.
"Some of the scorelines have been getting closer and closer and we really had to pull it of the bag to beat them earlier this year.
"We respect the quality they possess and know that on their day they are a very good side."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The Barbarians are one of the top invitational rugby sides with a long history and classic rugby jersey.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Lions get ready for their matches with this green training jersey. It's what the players wear. Get in the Gear!
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
$29.99
The Lions are ready to get their Australia tour underway. They arrive in Perth on Monday.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.