Who is already there? The Netherlands were the first European side to seal their spot. They have since been joined by England, Spain, Germany, Denmark, Serbia and Italy. In addition, Russia, Bosnia-Hercegovina, France and the Republic of Ireland are certain to be in the play-offs.
Who is in the mix for an automatic qualifying spot? Group 2 - Leaders Switzerland have every reason to be upbeat. A draw at home against Israel secures their passage to a second successive World Cup. But it's not all plain sailing - if they lose, Greece are likely to beat perpetual minnows Luxembourg and grab top spot at Switzerland's expense.
Group 3 - Slovakia are in the box seat, but if they fail to win in Poland, Slovenia will almost certainly pip them to top spot as their final game is against Europe's Worst International Team San Marino (played nine, lost nine, scored one, conceded 44).
Top spot in the other seven groups is already sorted.
What about these play-offs? You might have heard striker Wayne Rooney talking about his hopes that
Portugal will miss out
on the chance to once again shatter England's dreams in a quarter-final penalty shoot-out. He may yet be right - but Cristiano Ronaldo's boys are all-but certain to make the Group 1 play-offs as their final match is at home to Malta - yet to score in 810 minutes of World Cup qualifying action. A Portugal win secures second place.
Any more play-off chat? Israel will crash the Group 2 play-off party if they win in Switzerland and Greece stumble against Luxembourg. And Ukraine's webcast win over England on Saturday makes them hot favourites for the Group 6 runners-up spot, but if they blow it away to Andorra, Croatia can capitalise by beating Kazakhstan.
Who will miss out on the play-offs? As Group 9 had only five teams (the other groups have six), the eight best runners-up are judged after expunging results against the bottom-placed team in each group. Barring a Group 1 mathematical miracle (which involves various improbabilities including Malta thrashing Portugal in Guimaraes) the unlucky losers will be Norway.
When is the play-off draw and when are the play-offs? Fifa reveals its latest rankings on Friday 16 October. From that, the top four seeds will be nominated (the other four teams will be unseeded). Then, on Monday 19 October at 1300 BST, Fifa will make the draw in Zurich for the play-offs - keeping the seeded teams apart. The matches take place over two legs on Saturday 14 November and Wednesday 18 November. The Republic of Ireland are currently 38th in the Fifa rankings, and their hopes of being seeded are in the balance.
Tell me something unlikely Northern Ireland can still qualify for the World Cup. But to do so, they need to win against the Czech Republic in Prague and hope San Marino triumph against Slovenia, turning around a seven-goal deficit in the process. Unfortunately, that is the same San Marino ranked 203rd by Fifa whose all-time World Cup qualifying record reads: Played 45 Won 0 Drawn 2 Lost 43 Scored 8 Conceded 202
SOUTH AMERICA - One q'fying place/one play-off spot up for grabs
Who is already there? Brazil, Paraguay and Chile have filled three of the four automatic qualification spots in South America qualifying.
So where are Argentina? The Albicelestes have only failed to qualify once, in 1970 (they did not enter the 1938, 1950 or 1954 tournaments). They have reached every other World Cup and, of course, have lifted the famous trophy twice, in 1978 and 1986. But, with Diego Maradona at the helm, they are in a precarious position with one game to go.
What's the situation? Wednesday night's Uruguay v Argentina game (kick-off 2300 BST, live text on the BBC sport website) is effectively a play-off for the fourth and final automatic qualification spot in South America. The winners will qualify or, if it is a draw, Argentina will qualify (unless Ecuador win by at least five clear goals away to already-qualified Chile).
So are Argentina still strong favourites to qualify? There are many reasons for them to be nervous. Uruguay have been solid at home during qualifying - their only home defeat so far came against Brazil. Argentina have struggled on their travels, their only win coming at Venezuela at the start of their campaign. They have lost their last four on the road, three of those with Maradona as coach. BBC Sport's South America football expert Tim Vickery reckons the result is
a tough one to call.
And if they lose? A play-off berth is their best hope. But it is out of their hands - defeat means a win of any margin by Ecuador will put Argentina out.
Is anyone else in the mix? In all likelihood, Argentina, Ecuador and Uruguay are battling for the one automatic qualification spot or, failing that, the consolation of a play-off. But fans of obscure mathematical possibilities will note that Venezuela can grab the play-off place if Argentina thrash Uruguay, Chile beat Ecuador and they comfortably beat Brazil, somehow overturning a 15-goal deficit on Uruguay in the process.
What about this play-off? The fifth-placed team will play the team that finishes fourth in the North, Central America and Caribbean group in a two-legged play-off on Saturday 14 November and Wednesday 18 November.
NORTH AMERICA - One q'fying place/one play-off spot up for grabs
Who is already there? The United States and Mexico have already qualified from the rather wordily-titled North, Central America and Caribbean group.
Who might join them? It is a simpler picture than the other regions. Costa Rica and Honduras will, between them, fill the third and final automatic qualifying place and the play-off place in the early hours (UK time) of Thursday morning.
Who is confident? Costa Rica are in good shape. If Honduras fail to win in El Salvador, then they will qualify regardless of their own result away to the US. But if Honduras do win, Costa Rica will need to do likewise, as their goal difference is inferior to the Hondurans.
Who has the pedigree? Fans of vintage World Cup will note that Honduras have not qualified since Spain '82 where they were perhaps a shade unfortunate to go out in the first group stage. Costa Rica have done slightly better, qualifying in 1990, 2002 and 2006. Their 2006 campaign was rather weak, but in 1990 they beat both Scotland and Sweden on route to the second round.
AFRICA - Three of five qualifying places up for grabs
Who is already there? Ghana and Ivory Coast can rest easy - but plenty of teams face a tense day on 14 November, when qualification finishes.
Who is in the mix? Take one from two in each of the following pairings - Gabon or Cameroon, Tunisia or Nigeria, Egypt or Algeria.
Who is confident? Group A - African World Cup perennials Cameroon are looking good. They are through unless they get a worse result in their match against Morocco than Group A rivals Gabon get in their match in Togo. If they lose and Gabon draw, it will come down to goal difference.
Group B - Tunisia are sitting relatively pretty. The only way they will not qualify is if they fail to win away to Mozambique and Nigeria win in Kenya.
Group C - Egypt v Algeria is basically a straight fight for the qualifying spot. It is Algeria's unless Egypt can manufacture a handsome win on home turf.
One for the stat fans Here is a result to look out for - Egypt beating Algeria by two clear goals. If that happens the two teams will have an identical Group C record and will also be level on their head-to-head record.
That raises the prospect of lots being drawn to decide who qualifies. The only alternative is if the two teams can agree, in conjunction with Fifa, dates for a deciding play-off. But they will have to move fast - the draw for the finals is made on 4 December.
Anything else? Remember there are no scheduled play-offs in Africa, so it is first or nothing when it comes to bagging a World Cup berth. But most teams still have plenty to play for, as the top three teams in each group qualify for the African Cup of Nations in Angola in 2010.
ASIA & OCEANIA - One play-off winner to be decided
Who has qualified? The Asia and Oceania groups are almost done. Australia, Japan, North Korea and South Korea have qualified. The one remaining spot goes to the winners of a play-off between the Asia play-off winners Bahrain and the Oceania group winners New Zealand.
And when is this play-off? The first leg on 10 October finished Bahrain 0-0 New Zealand. The second leg takes place in New Zealand on 14 November - and four days later, the full list of participants for 2010 will be finalised.
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