With all of the home nations in action on Friday night and again on Tuesday, it is a decisive period as the groups take shape. Will England take pole position and what are the Republic of Ireland's chances? We preview the major issues here...
No pressure, lads
New FA chairman Greg Dyke may be targeting World Cup glory in 2022 but Roy Hodgson and his England squad have more immediate concerns over the coming days. While the Wembley date with Moldova on Friday should be routine, Tuesday's clash in Ukraine is key. Avoid defeat and England should be two home wins away from guaranteed qualification and the dreams of the Copacabana Beach can become a reality. Lose and top spot will be out of their hands. No pressure, lads.
No Rooney, no party?
Wayne Rooney might not be the main man at Manchester United but you can bet Roy Hodgson was having nightmares over his horror-movie head injury that sees the star forward unavailable for this World Cup qualifying double-header. Rooney scored the only goal of the game when these teams met at Euro 2012 last summer so someone else will need to step up if there is to be a repeat on Tuesday. Rickie Lambert may be the people's champion but Daniel Sturridge is the form man and even his silly dance celebration will be forgiven if the Liverpool striker can fire England to victory.
Crunch time for Trap
After a miserable performance at Euro 2012, Giovanni Trapattoni's Ireland kicked off this campaign with a fortunate escape in Kazakhstan and a 6-1 hammering at home to Germany to increase the pressure on the veteran Italian coach. There was then the disappointment of a last-gasp David Alaba goal for Austria to contend with too, but wins over the Faroe Islands in a tight Group C mean that the Republic are still in the hunt for second spot and a World Cup play-off in November.
With three points likely from the fixtures against Kazakhstan and Germany in October, their fate is likely to be decided by the events of the next week - Friday's home game against Sweden and Tuesday's trip to Austria. Four points could well be enough to make them favourites for the runners-up spot but any further slips will surely convince all concerned that the time is right for Trapattoni to move on.
He's spent much of the summer in the spotlight as the debate over his future raged but this weekend Gareth Bale might actually play some football - and it will be in a Wales shirt. Real Madrid's world record signing has not seen action in pre-season but that is unlikely to stop Chris Coleman pressing his star man into action for the games against Macedonia and Serbia. The qualifiers could act as a good chance for Bale to release some of that nervous tension that's build-up after an unprecedented week and it is perhaps to his advantage that his first performance as a Real Madrid player will not be under the gaze of a curious Spanish public. Even so, Bale's efforts are unlikely to go unnoticed or unanalysed.
Playing for the co-efficient
While the late turnaround at the Liberty Stadium in March that saw Croatia score twice in the final quarter of an hour ended any realistic hopes of reaching next summer's World Cup, Wales will be playing for the co-efficient in Macedonia in Friday evening. It's tough in Group A and the possibility of finishing bottom could consign a country to a decade or two of dismal draws being slung their way by the powers-that-be in that Swiss office. With a third-place finish still on offer for Wales and Bale potentially approaching his Real Madrid fuelled peak for 2018 qualifying there is plenty of reason to search for three precious points in Skopje.
A first-half goal from Robert Snodgrass was enough to give Scotland an unlikely victory in Croatia in their previous World Cup qualifier and there seems to be cautious optimism that Gordon Strachan can spark a mini-revival after the gloom of the Craig Levein regime. The win in Zagreb was a huge boost to Belgium's hopes of making it to Brazil next summer but Scotland will be looking to even things up between the top two by now taking three points off the group leaders in Glasgow on Friday evening. As Snodgrass himself told the pre-match press conference: "You take the belief and the no-fear factor and Scotland have a good chance, especially in front of a packed house at Hampden."
You never know with Northern Ireland
Six point from six games is about par for Northern Ireland in Group F. It's the fact that four of those points have come against Russia and Portugal but just a couple from home games against Luxembourg, Azerbaijan and Israel that is so baffling. Michael O'Neill's team were stirred into a stunning effort to beat Fabio Capello's Russia after the veteran coach made the mistake of belittling them on the eve of the game and a home game against Cristiano Ronaldo & Co should spark another cracking atmosphere at Windsor Park under the Friday night lights. Expect more glory against Portugal... And then defeat in Luxembourg on Tuesday.
Taking shape elsewhere
While the home nations battle away, several of the giants of international football will expect to book their place in Brazil next summer over the coming week. Their identities are familiar. Holland have an impeccable record in Group D and further wins in Andorra and Estonia will confirm their qualification. Four-time winners Italy can seal their passage with a couple of home victories, while three-time champs Germany will be there with a wins over Austria and the Faroe Islands. But how many teams from the British Isles will be joining them...