African champions Ivory Coast beat the Seychelles 7-0 away to stay one point ahead of Gabon in the Group F standings and they will qualify if they win their final game at home to Kenya on Tuesday.
Senegal maintained their two-point advantage in Group B over the Democratic Republic of Congo as both teams won away from home in their penultimate fixtures.
Senegal beat South Sudan 5-0 in Juba while the Congolese recorded a 1-0 triumph in Togo. Senegal will qualify for a third successive World Cup if they beat neighbours Mauritania at home in Dakar on Tuesday.
Ismaila Sarr gave Senegal a 29th-minute lead as Iliman Ndiaye delivered a cross to the back post from the right flank and the Everton winger was also the provider for Sadio Mane to score early in the second half.
Sarr then scored his second goal while Nicolas Jackson and Pape Cherif Ndiaye also found the net.
Cedric Bakambu broke away after an interception in the seventh minute to win the game for DR Congo in Lome, moving them to 19 points, two behind Senegal.
The Congolese complete their campaign at home against Sudan on Tuesday and, should they fail to overhaul Senegal, will be aiming to finish as one of the best four runners-up from the nine qualifying groups to go into an African playoff in November.
That offers a chance to compete at an intercontinental playoff in March for a place at the finals in Canada, Mexico, and the US
Ivorians awarded early penalty
The Ivorians were always expected to run riot against the Seychelles, who are 203rd out of 210 countries in the FIFA rankings, but were handed a gift of a penalty after six minutes, which Ibrahim Sangare converted to get things going.
After that followed goals for Emmanuel Agbadou, Oumar Diakite and Evann Guessand before halftime, and Yan Diomande, Simon Adingra and Franck Kessie after the break.
Ivory Coast advanced to 23 points with Gabon on 22.
