2018 World Cup play-off first leg: Northern Ireland v Switzerland
The Northern Irish are attempting to reach the finals for the first time since the 1986 World Cup in Mexico
They are also aiming to qualify for back-to-back major tournaments for the first time, having reached the last 16 at Euro 2016.
Higher-ranked Switzerland, on the other hand, are favourites to qualify for their fourth successive major tournament.
The second leg is in Basel on Sunday.
NI boss O’Neill believes his team are ready to rise to challenge again.
“This squad has evolved and has come through some bad times and learned from them,” he added.
“For some players, this may be their last opportunity and if they get to Russia it will be extremely well deserved.
“The one thing I would say to them is don’t fear the situation, embrace it 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.”