Lesotho edged Swaziland 1-0 in their quarter-final, while Zambia needed penalties to see off Namibia, who had the better of the chances in a fixture that finished 0-0.
The losing sides will move into the Plate competition semi-finals on Tuesday.
It was a day with just a single of goal, but both games provided rich entertainment, if perhaps not the required level of finishing.
Swaziland were the more vaunted team going into their tussle and had chances to win it but were stung by a fine strike from substitute Motebang Sera after 70 minutes of their encounter.
Lesotho will now await the winner of the tantalising quarter-final between defending champions Zimbabwe and in-form Botswana at the same venue on Sunday (kick-off 5.30pm; 3.30pm GMT).
Zambia edged Namibia 4-3 on penalties after an evenly contested 90 minutes that was perhaps just shaded by the Brave Warriors.
Vitapi Ngaruka had an early opportunity for Namibia but put his shot wide from the edge of the box, while at the other end prolific Zambian forward Lazarous Kambole found himself through on goal, but also missed the target.
Dynamo Fredericks then blazed wide from inside the box before Kelvin Mubanga launched a vicious shot at the Namibian goal that was well saved by Brave Warriors gloveman Maximilian Mbaeva.
Neither side could find a winner and the match went straight to penalties at full-time, where Zambia held their nerve to progress to a cup semifinal against the winner of Sunday’s quarter-final between South Africa and Madagascar (kick-off 3pm; 1pm GMT).
South Africa enter the competition with a youthful, inexperienced squad, but one that has been selected on form by coach Stuart Baxter.
There are a number of players that will be keen to stake a claim for a place in the squad for the African Nations Cup qualifier against Libya in September and after exiting at the quarterfinal stage last year, will be hopeful of a much better outcome this time around.
Madagascar topped Group A to win their place in the quarter-finals, taking seven points from a possible nine, with their key match the first, a 2-1 victory over Mozambique.
Zimbabwe have brought a strong squad as they seek to retain their trophy and extend their record number of wins in the competition to six. But they are up against a Botswana side that claimed a national record 6-0 win over Mauritius in their last match on Friday.
Coach Sunday Chidzambwa has led them to three titles and has yet to lose a match in the Cosafa Cup, going 15 games unbeaten to date.
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