The Brazilians were devastating in attack with the win booking their place in the semifinals where they will meet defending champions SuperSport United.
Following a tightly-contested opening period, Mogakolodi Ngele opened the scoring in the 22nd minute. The Botswana international latched onto a loose ball inside the area after Katlego Mashego failed to clear Ramahlwe Mphahlele's long throw.
A blunder from Stars’ Daouda Diakite put Sundowns 2-0 up four minutes later, with the Burkina Faso international punching the ball into the back of his own net after saving Leonardo Castro's initial attempt - the Colombian claimed the goal, but it was clearly an own goal.
Keagan Dolly continued his good run of form with a goal in the 36th minute. Man of the Match Ngele provided the perfect pass for the former Ajax Cape Town ace, who made no mistake from close range.
Danny Venter pulled a goal back for the hosts with a low drive on the stroke of half-time before first-half substitute Hendrick
Following a slow start to the second stanza, Themba Zwane restored 'Downs’
Bongani Zungu made it 5-1 three minutes later with a superb near-post header from a corner-kick, before striker Katlego Mashego put the icing on the cake - the former Orlando Pirates marksman saw his shot from range fly past Diakite in the 75th minute.
Sundowns host Matsatsantsa in the semifinals, with the winner to face either Kaizer Chiefs or Orlando Pirates in the showpiece.
Sundowns hit FS Stars for six
Cape Town - Three goals either side of the break guided Mamelodi Sundowns to a resounding 6-1 win over Free State Stars in a Telkom Knockout clash at Goble Park on Sunday.