Turkey, Northern Ireland’s next opponents, sit one point ahead of them on seven points.
Their meeting could therefore be crucial in terms of who secures second spot.
Turkey were the 1-0 victors when the sides met earlier in the campaign, but NI will take confidence from their performances under McArdle so far.
While the final two matches will not affect Northern Ireland’s World Cup play-off place, McArdle believes the outcomes could have longer-term consequences.
“The higher finish gives you that ranking for the next round of the Uefa Nations League for the draws,” McArdle said.
“The actual path one and path two [for the World Cup qualifiers] are still the same. It gives you slight seeding differences, but the effect that they have on path two are irrelevant.
“So, second and third, unfortunately, are very similar when it comes to the play-off qualification, but when it comes to next year’s seedings for the Nations League draw, it has a slight impact.”