Eight countries will join already-qualified Belgium at next year's World Cup in Russia when group play in the European zone is wrapped up over the next week.
There are two rounds of games still to be played, and Germany, England, Spain, Poland and Serbia look in strong positions to top their groups and advance.
The nine group winners will qualify automatically. The worst runner-up will be eliminated, with the other eight second-place teams entering a playoff round in November. The winners of the four playoffs also qualify for the World Cup.
Here is the state of play in the groups:
After missing out on qualifying for the European Championship last year, the Netherlands could be out of the World Cup race by the end of the weekend.
A three-time World Cup runner-up, the Dutch will miss their second straight major tournament if they can't match Sweden's result.
The Netherlands is third in the group, four points behind leader France and three behind second-place Sweden. The Dutch play at Belarus on Saturday, when Sweden hosts Luxembourg. Playmaker Wesley Sneijder has been dropped and winger Ryan Babel has been recalled for the first time in six years for the crucial game.
The French will clinch first place and automatic qualification if they win in Bulgaria on Saturday and Sweden loses against Luxembourg. France would guarantee a top-two finish with a win.
Even after seven straight wins - and an expected eighth at Andorra on Saturday - European champion Portugal is not sure to be at the World Cup.
Group leader Switzerland has won eight straight, including an opening 2-0 victory over a Portugal team without Cristiano Ronaldo, ahead of hosting Hungary on Saturday.
It all points to a showdown in Lisbon next Tuesday to win the group and take the direct qualifying place. The Swiss currently lead by three points.
Portugal has the edge if goal difference is the tiebreaker. Helped by Ronaldo's European-best 14 goals, Portugal is already nine superior to the Swiss before facing Andorra, which it already beat 6-0 at home.
Hungary's drop in form since Euro 2016 means the Faeroe Islands can go third by beating Latvia on Saturday.
Germany needs only one point from its final two games, against Northern Ireland in Belfast on Thursday or Azerbaijan in Kaiserslautern three days later, to ensure qualification as group winner.
The world champions have eight wins from eight games and coach Joachim Loew said that anything less than 10 wins from 10 would be a disappointment.
Goalkeeper Manuel Neuer, defender Jonas Hector and forward Mario Gomez are out with injuries, while Loew also omitted midfielders Mesut Ozil and Sami Khedira because of a right knee problem and right thigh strain, respectively.
Germany has 24 points, five more than Northern Ireland, which is already assured of second place.
Serbia leads by four points and will earn automatic qualification by beating Austria on Friday.
It looks to be a fight between second-place Wales and third-place Ireland for the runner-up spot - they are separated by one point and meet in Cardiff in the final round of games on Monday.
Before then, Wales visits Georgia and Ireland hosts Moldova.
If Serbia doesn't guarantee first place in Vienna, it has a second chance in a home game against Georgia on Monday.
Group leader Poland needs just a point from its game against Armenia in Yerevan to be assured of a top-two finish, while Montenegro and Denmark can both still qualify automatically ahead of their clash in Podgorica.
However, if Montenegro and Denmark - both on 16 points, three less than Poland - draw in Podgorica, Poland can qualify automatically with a win on Thursday.
Otherwise, Poland faces a potential group-decider at home to Montenegro in Warsaw on Sunday, when Denmark hosts Romania in Copenhagen.
Poland is hoping its 4-0 loss in Denmark on Sept. 1 does not prove decisive.
England leads its group by five points and needs only a point from its last two games, at home against Slovenia and at Lithuania, to secure first place.
If England beats third-place Slovenia at Wembley Stadium on Thursday, second-place Slovakia will be guaranteed to finish as runner-up with a win at Scotland.
Scotland has won three of its last four qualifiers to move level on points with Slovenia in fourth place, and could be in second place heading into the last round of games if it wins against Slovakia.
In the last round Sunday, Scotland travels to Slovenia and Slovakia hosts Malta.
Spain has a three-point lead over Italy and can close in a World Cup spot with a victory at Albania on Friday.
Spain has a much better goal difference than Italy (29 to 12), so it will likely win the group even with a setback in one of its final two qualifiers.
Italy hosts Macedonia on Friday and plays at Albania on Monday, when Spain visits Israel. The Azzurri, who are without injured midfielder Marco Verratti, need one point from its final two qualifiers to secure second place and a playoff spot.
Spain coach Julen Lopetegui won't be able to count on Andres Iniesta, Alvaro Morata and Dani Carvajal because of injuries.
With Belgium already qualified, Bosnia and Greece are in a battle for second place in the group.
Bosnia has a one-point advantage but an arguably harder task, hosting the Belgians Saturday with an injury-plagued squad. Haris Medunjanin of the Philadelphia Union was one of four late replacements. The Bosnians' last game is at Estonia as they look to reach a second straight World Cup.
Greece is at Cyprus and then at home against Gibraltar, and has recalled attacking midfielder Lazaros Chrsitodoulopoulos after an 18-month absence.
In the tightest European group, the top four teams are separated by only two points. Group leader Croatia and Iceland have 16 points each, while Turkey and Ukraine are both two points behind.
Croatia hosts Finland on Friday and travels to Ukraine for the last match on Monday, while Iceland plays at Turkey and hosts Kosovo. Turkey plays the last game at Finland while Ukraine travels to Kosovo on Friday.
Because of its poor results in the team's first attempt to qualify for a World Cup, Kosovo coach Albert Bunjaku has agreed to leave his post at the end of qualifying. Kosovo was accepted by UEFA and FIFA last year, and fast-tracked into World Cup qualifying.
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