Egypt can become the second African country, after Nigeria to book their trip to Russia next year if they beat Congo at home on Sunday.
Tunisia also stand on the brink of a place as they maintained their three-point lead at the top of their group with one match left to play.
The other two groups remain in the balance and will be settled on the last match day in November.
The African qualifiers come from the five group winners.
Alex Iwobi’s second-half winner ensured Nigeria became the first African nation to qualify for the 2018 World Cup when their 1-0 home victory over Zambia on Saturday moved them into an unassailable lead in their group.
Iwobi netted with a neat finish inside the box in the 73rd minute of an open contest in Uyo after both Wilfred Ndidi and Moses Simon had squandered earlier chances.
Zambia were the only country still capable of catching Nigeria in Group B but needed an unlikely away win against the Super Eagles, who have now qualified for six of the last seven World Cup finals, missing out only in 2006.
Nigeria advanced to 13 points with Zambia on seven, one ahead of third-placed Cameroon, who beat Algeria 2-0 in Yaounde earlier on Saturday.
Egypt will return to the finals for the first time since 1990 if they beat the bottom-placed Congolese in Alexandria after their closest rivals in Group E, Uganda, were held at home to a goalless draw by Ghana in Kampala on Saturday.
Victory would see the Egyptians move into an unassailable four-point lead and render their last match away in Ghana of academic interest only.
Youssef Msakni’s hat-trick saw Tunisia come from a goal down to beat Guinea 4-1 away in Conakry and stay three points ahead of the Democratic Republic of Congo in Group A.
Liverpool-bound Naby Keita scored first for Guinea but Msakni equalized in stoppage time at the end of the first half and added two more after the break with Mohamed Amine Ben Amor also scoring.
Tunisia need just a point from their last game at home to neighbors Libya next month to qualify.
Firmin Mubele scored a 74th-minute winner for DR Congo as they beat Libya 2-1 in Monastir, Tunisia, where the Libyans have been forced to host matches because of a FIFA ban dictated by safety concerns in their strife-torn country.
Morocco will also need only a draw from their last game to finish top of Group C after they beat Gabon 3-0 in Casablanca on Saturday to set up a showdown with Ivory Coast, who are a point behind them.
Victory for the Elephants would take them to the finals instead – for a fourth successive tournament.
Senegal moved to the top of Group D with a 2-0 away win over the Cape Verde Islands as England-based Diafra Sakho and Cheikh Ndoye scored late, while 2010 World Cup hosts South Africa remained in the race by beating Burkina Faso 3-1 at Soccer City.
A disputed goal after just 48 seconds set South Africa on their way to a 3-0 half-time lead as they looked to bounce back from the embarrassment of double defeats by the Cape Verde last month.
Senegal have eight points, Burkina Faso and the Cape Verde six and South Africa four, but Senegal and South Africa have an extra game to play.
The last round of World Cup qualifiers will be played between Nov. 10 and 14.