Switzerland head back to the Alps with a slender lead from the first leg, after scoring a controversial penalty in Northern Ireland on Thursday.
The Irish, who are seeking to reach their first World Cup since 1986 will be fired up and keen to ruin the Swiss home party.
Michael O’Neil is missing Corry Evans, who is suspended after picking up his second booking in the first leg.
That means that Millwall’s George Saville could be in line for his first start, having made sub appearances against Germany and Norway.
Stuart Dallas looks set to be out injured whilst Kyle Lafferty is set to drop to the bench.
Switzerland are missing Valon Behrami and Johan Djourou through injury.
Northern Ireland need to let go of any anger over Thursday’s penalty and channel it here instead.
If can do that, they can use whatever energy they have to push forward and terrorise the Swiss.
Switzerland have been in a similar position before, having to qualify for the 2006 FIFA World Cup via play offs.
Back then, they won their home leg against Turkey before losing the away game but qualified on away goals (4-4 aggregate).
This time, they would need to lose 2-1 to qualify via away goals but I am backing Northern Ireland to go and achieve the impossible here.
Prediction: Switzerland 0-2 Northern Ireland
Result: Switzerland 0-0 Northern Ireland (Switzerland reach 2018 FIFA World Cup 1-0 on aggregate)