As the focus shifts to the knockout stages, the Proteas will be glad to have won their final league game batting second.
Losing another toss would not result in losing another game, as was the case against India. Because this time, the Proteas were more convincing with the ball and much better with the bat.
Gerald Coetzee was the star in the first innings, picking up 4/44 in his ten overs. Azmatullah Omarzai held his ground for an unbeaten 97, ensuring a respectable total of 244 after being 116/6 at one stage.
In the second innings, everyone chipped in, but it was van der Dussen (76*) and Andile Phehlukwayo (39*) who got the two points on the board.
The result put an end to any underlying chances Afghanistan had of progressing and South Africa will now face Australia in Thursday's semi-final.
The first semi-final is almost certainly set to be between log leaders India and New Zealand, who currently occupy the fourth spot.
Pakistan face England on Saturday and would need more than a miracle to stand any chance.
Batting second, Pakistan need to chase down England's target in 15 balls or less to edge the Kiwis on net run rate in the table.