The Brazilians made three changes with Ricardo Goss, Ricardo Nascimento and Lesedi Kapinga coming into the side. TTM, meanwhile, made one change with Ndabayithethwa Ndlondlo coming into their starting line-up.
With 10 minutes gone, Lesedi Kapinga dropped a shoulder to beat his opposing defender and tried to curl one towards the far post corner but it was too straight and in the end a comfortable effort to deal with.
Sundowns were totally dominating, but were perhaps being a little too intricate in their passing and not quite incisive enough.
There were not many chances created as the sides went into the interval goalless, with TTM looking solid at the back against the holders.
Sundowns almost took the lead two minutes into the second half when Thapelo Morena's long ball over the top of a TTM defence that was holding a high line was run onto by Siphelele Mkhulise, who lobbed the onrushing Washington Arubi but the ball was heroically cleared away just before crossing the line by Alfred Ndengane.
The Brazilians missed a chance that had goal written all over it in the 55th minute. Sirino fizzed a testing ball into the area from the right-hand side which Arubi could only parry right into the path of Zwane, who skied an easy close-range effort over the bar.
Aubrey Modiba then backheeled the ball down the left-hand line for Lyle Lakay, who whipped in a good cross which Sirino met with his head and it brought a good save out of Arubi down to his right.
With three minutes to, Downs built up from the back well with Shalulile involved and Vilakazi shot from close range, but Arubi made the save while TTM's high line was once again exposed but Vilakazi failed to capitalise firing over the bar from a tight angle.
Lakay tested Arubi once again eight minutes into stoppage time when he struck a free-kick just outside the box which looked destined for the top-right hand corner but it was brilliantly diverted away by the diving Zimbabwean shot-stopper.
The tie went to penalties and the sides each netted their opening five. However, Hlompho Kekana missed the sixth and Thembisani Nevhulamba tucked home TTM's sixth to send them into the final of South Africa's premier cup competition.
Sundowns: Goss, Morena, Modiba, De Reuck, Nascimento, Coetzee, Kapinga, Mkhulise, Zwane, Sirino, Shalulile
Subs: Mweene, Mvala, B. Onyango, Vilakazi, Maluleka, Mkhuma, Kekana, Motupa, Lakay.
Tshakuma: Arubi, Lukhubeni, Nonyane, Thopola, Ndengane, Theron, Manaka, Mnyamane, Ngema, Rantie, Ndlondlo.
Subs: Mamudzidi, Molongoane, Madhanaga, Bereng, Nevhulamba, Thangwane, Mphambaniso, Timm, Ngele.