O'Neill is looking to lead the Green Army to their first World Cup since 2002 after earning a place in the eight-team playoffs with the runners-up spot behind Serbia in Group D.
Ireland would likely take a draw from Saturday's clash in Copenhagen, but O'Neill has hinted that is not currently the mindset within his squad.
O'Neill is quoted by The Mirror as saying: "These are tough matches, but we've put ourselves in this position — so don't die wondering. Getting to the Euros last summer was big, but this is even bigger and getting there would be fantastic.
"Over these two matches, we have to find ourselves in front. We remain unbeaten away from home in this campaign, which is no mean feat and testament to the character of the side.
"While every international side has limitations, we'll try to stay as strong as we can and play to our strengths which is the most important thing - and something we always do."
Ireland head into the game having recorded successive wins over Moldova and Wales.