Northern Ireland skipper Aaron Hughes admits they are facing their biggest game in years when they tackle Slovakia on Wednesday.
The Northern Irish would put themselves in pole position for a top-two spot if they could beat group leaders Slovakia at Windsor Park.
Northern Ireland have not qualified for a major tournament since 1986 and Hughes knows that their clash with Slovakia is the biggest during his time playing for his country.
"It is going to be up there, in terms of what it means," Hughes told Sky Sports News.
"We have had some big games in terms of opposition in who we have come up against but this is it in terms of what it means.
"We had a good result on Saturday which makes this one even bigger."
Boss Nigel Worthington insists that they will not be taking Slovakia for granted.
"We have got to be very, very cautious, they have been top of the table all the way through, they are well organised, they are solid, they work hard," he told Sky Sports News.
"We have got to be patient and concentrate on our own game - but if we do it right, then we can get the result we all want, which is a win and 17 points with one game remaining."
Worthington will be making changes for the game with Kyle Lafferty sidelined through injury.
Burnley's Martin Patterson will come in to replace the Rangers man, and Worthington has no qualms about bringing him in.
"I haven't got bags and bags of centre forwards, we have Martin - I said to him I don't care what chances you miss as long as you work hard for the team," he said.
Worthington will also have Chris Brunt and Chris Baird available again after they both missed the draw in Poland last weekend.