Brazil became the first side to qualify for next year’s tournament, while South American rivals Argentina face the very real prospect of failing to reach the World Cup for the first time since 1970.
Elsewhere, the battle between Spain and Italy looks set to go to the wire in Europe, while Uzbekistan have an outside chance of reaching their first World Cup.
Here, we take an in-depth look at all of the World Cup qualifying sections…
EUROPE: ITALY AND SPAIN LEVEL PEGGING
Two of Europe’s heavyweights are neck-and-neck in Group G. Wins in March for both Italy and Spain leave the duo on 13 points, while their meeting in Madrid on September 2 could well decide who qualifies automatically and who drops into a play-off spot.
A perfect start for Switzerland (five wins from five) sees them three points ahead of Euro 2016 winners Portugal in Group B, while Germany are looking comfortable in Group C as maximum points so far leaves them five clear of Northern Ireland.
Group F leaders England are four points better off than Slovakia, while Poland have a stranglehold on top spot in Group E as four wins and a draw put them six points clear of both Montenegro and Denmark.
It’s too close to call in Group D currently – Serbia and the Republic of Ireland are level on 11 points, with Wales and Austria four adrift and at risk of missing out.
Group H remains tight with Belgium narrowly ahead of Greece and Bosnia, while Croatia are first in Group I with Iceland, Ukraine and Turkey in pursuit.
The nine group winners qualify automatically for the World Cup, while the eight best runners-up are paired into a two-legged play-off for the right to reach Russia.
SOUTH AMERICA: ARGENTINA IN PERIL
Just six points separate second-placed Colombia with Paraguay in eighth, while Argentina currently sit out of the automatic positions after losing 2-0 in Bolivia. La Albiceleste are also without Lionel Messi for a further three games after he directed insulting words at an assistant referee and missed Tuesday's defeat to Bolivia.
Colombia’s 2-0 win in Ecuador saw them move above Uruguay, who slipped to third in the standings following a 2-1 defeat at Peru – a result which ultimately guaranteed Brazil’s qualification.
Meanwhile, Chile leapfrogged Argentina into fourth with a 3-1 win over Venezuela.
Qualified: Brazil (1/4.5)
The top four qualify automatically for the World Cup, while the fifth-placed team faces a two-legged play-off against the winners from the Oceania section.
ASIA: UZBEKISTAN FOR RUSSIA?
It’s looking good for Iran in Group A – two wins in March puts them four points clear at the top ahead of South Korea, who hampered Syria’s chances with a narrow 1-0 win on Tuesday.
Uzbekistan are just one point behind South Korea (with the top two qualifying automatically) following their 1-0 victory over 2022 World Cup hosts Qatar, who sit bottom after one win, one draw and five losses.
Read the full article on eurosport.co.uk: Road to Russia 2018: Brazil through, but who’s in danger of missing out?