Whereas Switzerland have qualified for the previous three World Cups, numerous Northern Irish generations have never been to the tournament so O'Neill is wary of the magnitude of this tie for the entire country.

And he believes his team are ready to rise to the challenge.

"I see in this squad an opportunity they don't want to waste," O'Neill said.

"But equally they've done everything so far and I think they will do everything in the next two games to make it a reality.

"These players have experienced a lot of good and bad.

"The one thing I would say to them is don't fear the situation, embrace the situation and make sure whatever happens when you look back there are no regrets.

"We all know the prize is massive and what it means to everyone in Northern Ireland, the players, staff, Irish Football Association, everyone in Northern Ireland.

"Our focus is on how we get through the two games and I see a reassurance in the players and self-belief that has grown over a period of three to four years and put them in this position."

Just being in this position is an achievement given how bleak things had been in previous qualification campaigns.

Northern Ireland were 129th in the world rankings early on in O'Neill's tenure and, when they last faced Switzerland in 2004, they were in the midst of a run of winning just one game in almost four years.

"It wasn't an overnight fix and it never will be when you're a small country," O'Neill said.

"The players deserve enormous credit, they had to turn it around themselves. You can get into a habit of things being poor and losing and that mindset. It takes guts to change it and the players did that. That's something we hang onto.

"The good thing we have now is that when you've been through those experiences, you don't want to go back. That's the only motivation you need to maintain at the level it's at, for us to progress to the (Euro 2016) finals, to get to the last 16, to now being in a World Cup play-off.

"The players don't want to let it go."

Jonny Evans is one of those who knows about the dark days.

The 65-cap West Brom defender, whose brother Corry will also likely start against the Swiss, showed his softer side when he cried following the win over Ukraine at the Euros.

Representing his country is still something that chokes up Evans, and his emotions are frequently stirred by O'Neill's motivational tactics.

"I still get emotional; it is a weird thing," Evans said.

"Every time we come to an international, Michael gives us these motivational videos at various times during the week and you feel yourself getting emotional.

"Playing for your country does that to you. We have all come through a lot together as a team, and you get those emotions."

Veteran defender Aaron Hughes (calf) trained on Wednesday and O'Neill said that both he and Paddy McNair, who is only just back from a long-term knee injury, are in contention to feature in the first leg at Windsor Park on Thursday.