And South African made full use of the conditions, especially by Morkel. Though South Africa was expected to win against Afghanistan, a convincing win was necessary to carry the momentum to the Super Eights.
The lanky pacer picked up four for 20 in three overs to help his team sail through to the Super Eight stage.
The Afghan batting display showed a gulf in technique and experience as the top order proved unable to cope with pace, with Morkel taking three wickets in one over itself.
At times, the Afghan batsmen looked unnerved by the pace and bounce of the Kensington Oval pitch and none of their top seven Afghan batsmen made double figures.
They slumped to 25 for seven before Mirwais Ashraf restored some pride and provided the crowd with some excitement, hitting two sixes in his spirited 23 from 25 balls.
Earlier, Graeme Smith and Jacques Kallis provided the backbone to a largely unconvincing South African batting display.
For Afghanistan Hamid Hasan was the pick of the bowlers, picking up three for 21 in his three overs.