Two first half goals from West Ham United’s Diafra Sakho and an own goal from Thamsanqa Mkhize secured Senegal’s second World Cup qualification, their first since Korea/Japan 2002.
Going into the game, South Africa needed an outright win to give hope to their slim chance of making it to Russia.
The win took Senegal to an unassailable 11 points after five games, while South Africa remain rooted at the bottom on four points.
Sakho put Senegal 1-0 up in the 12th minute as he slid the ball past Itumeleng Khune after he was set up by a sublime Sadio Mane pass.
In the 38th minute, Senegal doubled their lead following an unfortunate own goal by Thamsanqa Mkhize after Khune had saved Mane’s initial attempt.
Senegal have now joined Nigeria and Egypt as the three African countries who have so far qualified for the 2018 World Cup.
Senegal will host South Africa on Tuesday, November 14 in an inconsequential game in their last African qualifying Group D fixture.
Meanwhile, Group D’s other teams, Burkina Faso and Cape Verde, will do battle in Ouagadougou in another inconsequential match.
Burkina Faso currently occupy second place on six points, while Cape Verde also on six points are third.