South Africa rode on Marizanne's unbeaten 150-ball 102 to post 207 for five in their alloted 50 overs after electing to bat and then shot out Pakistan for a paltry 81 in 29.4 overs to finish the league with two points from three games.
Pakistan remained winless in the tournament after having lost their other two Group 'B' games to Australia and New Zealand.
Marizanne also contributed with the ball, picking up three key Pakistani wickets for 18 runs to help the Proteas register their first win in the ongoing World Cup.
Marizanne, who scored her maiden hundred, was involved in a record century-plus stand for the unconquered sixth wicket partnership with Dane Van Niekerk (77-ball 55 not out) after the South Africans were left tottering at 79 for five in 23.5 overs.
Both joined forces at a time when Pakistan's new-ball combination of Asmavia Iqbal and Qanita Jali had reduced the Proteas to 55 for four inside 17 overs.
Just as South Africa began to build a partnership, Susan Benade was run out by Javeria Khan.
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It was then left to Marizanne and Niekerk to resuurect the innings and provide some semblance of respectability to the score.
Both mixed caution with aggression and added 128 runs for the sixth wicket, the highest partnership for South Africa in the World Cup and the second highest sixth-wicket partnership of all time.
Pakistan started off their run-chase on a shaky note and kept losing wickets at regular intervals. Their ploy to promote Jalil up the batting order and bringing skipper Sana Mir lower down the order did not pay off as they folded up for another low score in the tournament. MORE