The Brazilians scored with just a minute on the clock when Gaston Sirino scored. But an equaliser shortly before half time from Lebohang Maboe and two late goals made it an historic day for the Team of Choice.
Looking to subdue the fired-up home side and their supporters, Sundowns made the perfect start when Percy Tau played in Sirino, whose shot from a tight angle went straight through the hands of home keeper Richards Ofori and into the back of the net.
Maritzburg struggled to get going with their usual high-energy football and with the exception of a Bevan Fransman free kick which sailed over the bar on 25 minutes, never looked like threatening the 'Down goal.
The Tshwane team meanwhile looked comfortably in command and were close to adding a second goal in the 41st minute when some neat interplay opened up a chance for Sibusiso Vilakazi, but this time Ofori came up trumps with a good diving save before Tau blasted the rebound wide.
The KZN side then suddenly sprung to life and started to find some more fluency in their play, keeping Sundowns back in their own half in the closing minutes of the first half.
And they were rewarded with a 43rd minute equaliser after Fortune Makaringe combined with Lebohang Maboe, the latter showing great skill to create space in the box, which resulted in him nailing an unstoppable low drive across goal and in at the far corner.
With the game all square, the second half saw the teams evenly matched as both probed for chances, but there were few openings in the respective defences.
Sundowns did manage to carve out a few opportunities as the match moved into the last 25 minutes as Vilakazi's curler from a very tight angle dipped onto the roof of the net before Ofori went flying through the air to keep Sirino's shot from finding the top corner.
Masandawana had been starting to exert some extended pressure on the home defence, only to suffer a setback in the 75th minute when Sirino was sent off after a second yellow card, the visitors already having had to replace an injured Anele Ngcongca with Thapelo Morena earlier in the half.
The game was there for the taking, and it was Maritzburg substitute Mxolisi Kunene who made himself a hero when he turned sharply just inside the box before firing in a brilliant low shot into the far corner with five minutes to go.
The hosts had to withstand some considerable late pressure, but having done that, they hit Sundowns with a late sucker punch when Makaringe finished neatly after swift counter attack in added time.
Fadlu Davids' Maritzburg side will meet Free State Stars in the final in Cape Town after Stars' 2-0 win over Kaizer Chiefs on Saturday night.
Maritzburg: Ofori , Sanoka, Fransman, De Reuck, Xulu, Makaringe, Shandu, Maboe, Ndlovu, Fileccia, Mekoa.
Subs: Mpandle, Mokate, Matima, Kunene, Atouba, Van Wyk, Thlone.
Sundowns: Onyango, Langerman, Ngcongca, Arendse, Nascimento, Mabunda, Vilakazi, Manyisa, Sirino, Zwane, Tau.
Subs: Brimah, Madisha, Makgalwa, Morena, Zulu, Brockie, Laffor.
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