Although Belgium and Brazil have secured their places at the 2018 World Cup in Russia, while England and Germany are on the verge of qualifying, it hasn't been plain sailing for some of the other big nations.
As we head into the crunch final round of games, a few of the countries who would have been odds-on for qualification face a pressure-packed double-header between now and Tuesday night.
Although international breaks are often looked upon with scorn, this batch of fixtures is sure to provide thrills and spills aplenty.
Netherlands, finalists at the 2010 World Cup in South Africa, are in danger of missing their second consecutive major tournament, having also failed to qualify for Euro 2016.
Now managed by former Sunderland boss Dick Advocaat, the Dutch will have to beat Belarus away and Sweden at home for a chance to make the play-offs.
They are currently three points behind Sweden in Group A with an inferior goal difference, so if Sweden beat Luxembourg at home, which they should, Advocaat's side will have to beat Sweden comfortably to keep their hopes alive.
Meanwhile, the Republic of Ireland must beat minnows Moldova in Dublin on Friday night before travelling to Wales on Monday. Wales are one point ahead of Martin O'Neill's team, so it looks as though it will come down to the wire in Group D.
Despite the excellent form of Tottenham Hotspur's Christian Eriksen, Denmark are third in Group E and only a win will do in Montenegro – who are second – on Thursday.
Scotland haven't qualified for a World Cup since 1998 and that won't change unless they win both remaining matches against Slovakia and Slovenia. It's going to be a massive ask for Gordon Strachan's men.
The USA have been ever-present at the World Cup since 1986, but to ensure they make an eighth successive tournament, they must avoid a slip-up against Panama and Trinidad & Tobago in their final two games.
Argentina have Chile breathing down their necks in the CONMEBOL qualifying group. Jorge Sampaoli's men are currently fifth, the sole play-off spot, with Chile a point behind in sixth. Facing Argentina are tricky games at home to Peru, who are currently fourth, and away to Ecuador.
The last time Argentina missed out on the World Cup was 1970 – surely Lionel Messi and co will pull through?