A look at the possible permutations ahead of the final rounds of the European World Cup qualifying competition:
The winners of the nine groups qualify directly for Russia next year. The eight best runners-up will take part in two-leg playoffs for four more places.
The results against the bottom-placed teams in the group do not count in determining the best runners-up.
(France 17 points, Sweden 16, Netherlands 13, Bulgaria 12, Luxemburg 5, Belarus 5)
France will qualify on Saturday if they win away to Bulgaria, but only in the unlikely event of Sweden also losing at home to Luxemburg.
The Netherlands will be eliminated if they lose away to Belarus and Sweden draw or win. The Dutch will also be knocked out if they draw, while Sweden win and France at least draw.
Luxemburg and Belarus are already eliminated.
(Switzerland 24, Portugal 21, Hungary 10, Faroe Islands 8, Andorra 4, Latvia 3)
Only Switzerland and Portugal can finish in the top two. The Swiss will win the group if they beat Hungary at home and Portugal fail to beat Andorra away on Saturday.
If both teams win, the group will boil down to a showdown in Lisbon on Oct 10. Unless Switzerland score a hatful of goals against Hungary, a Portugal win in that match will guarantee top spot for the European champions, whose goal difference is better by nine than the Swiss.
(Germany 24, N.Ireland 19, Azerbaijan 10, Czech Republic 9, Norway 7, San Marino 0)
Only Germany and Northern Ireland can finish in the top two. They meet in Belfast on Thursday where a point for the world champions will be enough to win the group.
(Serbia 18, Wales 14, Ireland 13, Austria 9, Georgia 5, Moldova 2)
Serbia will qualify if they win away to Austria on Friday or if they draw and Wales and Ireland fail to win. They will also qualify with a defeat, if Wales lose and Ireland fail to win.
Wales, who are away to Georgia, will guarantee a top-two finish if they win and Ireland lose at home to Moldova, although the latter is unlikely.
Austria’s only hope to avoid elimination is to beat Serbia and hope that Wales and Ireland both fail to win. Georgia and Moldova have been eliminated.
(Poland 19, Montenegro 16, Denmark 16, Romania 9, Armenia 6, Kazakhstan 2)
Poland will qualify if they win in Armenia on Thursday and Montenegro draw at home to Denmark, while a point will guarantee the Poles a top-two finish provided Montenegro and Denmark do not draw.
Montenegro need to win to maintain a realistic chance of a top-two finish as their final match (Oct. 8) is away to Poland while Denmark will host eliminated Romania. Armenia and Kazakhstan are also out of the running.
(England 20, Slovakia 15, Slovenia 14, Scotland 14, Lithuania 5, Malta 0)
England will qualify if they win at home to Slovenia on Thursday while a draw will also do the trick if Slovakia fail to beat Scotland away. Slovakia will clinch second place if both they and England win, leaving Scotland and Slovenia eliminated.
Lithuania and Malta are out of contention.
(Spain 22, Italy 19, Albania 13, Israel 9, Macedonia 7, Liechtenstein 0)
Spain, who are guaranteed a top-two finish, will qualify if they beat Albania at home on Friday and Italy drop points at home to Macedonia, although the latter seems unlikely.
Assuming Spain and Italy both win, then Spain would need a draw in their final match away to Israel to guarantee qualification.
Italy need a draw against Macedonia to ensure a top-two finish and end Albania’s faint hopes of qualifying. Macedonia, Israel and Liechtenstein have all been eliminated.
(Belgium 22, Bosnia 14, Greece 13, Cyprus 10, Estonia 8, Gibraltar 0)
Belgium have qualified while Estonia and Gibraltar are out.
Bosnia can make sure of second place if they beat Belgium at home on Saturday and Greece lose away to Cyprus. Meanwhile, the Cypriots can only continue to dream of a first World Cup appearance if they beat Greece and Bosnia drop points, or they draw with Greece and Bosnia lose.
(Croatia 16, Iceland 16, Turkey 14, Ukraine 14, Finland 7, Kosovo 1)
No team can win the group on Friday when Croatia host Finland, Turkey entertain Iceland and Ukraine visit Kosovo.
Only Finland and Kosovo have no chance of qualifying.
Turkey would be eliminated if they lost to Iceland, and Croatia win. Ukraine will be eliminated if they draw or lose, and both Croatia and Iceland win.