O’Neill’s men welcome Greece to Windsor Park tonight, and will be roared on by 12,000 fans who know victory will ensure a first major tournament appearance since the 1986 World Cup.
A first ever European Championship appearance would also be theirs if Hungary fail to beat the Faroe Islands, and the prospect of becoming history makers is now tantalisingly close.
O’Neill, whose own international playing career spanned the fallow years between 1988 and 1996, knows better than most how important that would be for the current generation.
“As an international player you write your legacy in terms of the number of times you play, the number of memorable performances you have and if you get the chance to go to a major tournament,” he said on the eve of the match.
“These players can write their legacy by going to a major tournament.
“The prize is great and it’s something the players are determined to be part of. These opportunities don’t come around for Northern Ireland players very often.”
Northern Ireland finished fifth in qualification for the 2014 World Cup, O’Neill’s first campaign at the helm, and slipped down from the fourth to the fifth seeding pot as a result.
But their recent performances have stood in stark contrast to that lowly ranking and O’Neill has been eager to remind his players of their efforts.
“All week the preparation has been around our strengths, what has made us successful in this campaign, re-emphasising that,” he said.
“We are the top goalscorers in the group and we’re unbeaten at home.
“It’s a case of belief. A case of trust among each other. That belief has grown game by game.”
Victory last month over Hungary would have sealed qualification, but a 1-1 draw kept Northern Ireland waiting.
Captain Steven Davis has experienced some great nights with his country, not least when he played in the famous 1-0 win over England a decade ago, but he is happy to admit tonight’s game could top the lot.
Asked if it was the biggest match of his career, the Southampton midfielder said: “Without a doubt, there’s huge significance on the result.
“It’s hard to sum up in words really what it would mean. We’re so close yet so far at this point in time.
“I don’t think there’s any nerves, it’s excitement in the build-up to the game.
“We can’t wait to get back out there and that’s been the case since the final whistle against Hungary.
“We’re just looking forward to the game and can’t wait to get started.”
Windsor Park has been under construction for the entirety of the Group F campaign, with reduced capacities as a result. The Irish FA was eager to increase capacity from the 10,700 who watched the Hungary game, and an additional allocation of 1,500 tickets was snapped up in just three minutes last week.
Those fans are sure to generate a frenzied atmosphere, and O’Neill is sure they can play their part.
“The increased capacity of the stadium will make a huge difference, particularly on that side of the pitch,” he said. “The noise level against Hungary was phenomenal. I felt the supporters played a huge part on the night.
“That inspiration comes from the 12,000 people who will be here willing the players to get the job done.”