Eagles, who have gone through a mammoth four coaching changes this season, were given an early heart-in-the-mouth moment, with Deolin Mekoa finding the post following quick interplay.
Mohau Mokate ran through onto a delightful delivery from Lebohang Maboe, but was unable to make the opportunity count.
The aerial prowess of Mame Niang, as expected, proved troublesome for them as the lanky Senegalese fought tooth and nail for every ball.
The Team of Choice's chances to continue their dominance took a knock with the dismissal of Bevan Fransman before half-time following a second bookable offence.
However, it didn’t stop them from going in front after good work on the left by Siphesihle Ndlovu freed Mekoa to finish at the far post in first-half stoppage time.
After fluffing a few chances after the break, United were made to pay after the home side converted the equaliser from the penalty spot courtesy of Niang 20 minutes from time.
The game was brought to a halt in the 82nd minute when heavy lightning and thunderstorms forced the officials to temporarily suspend the encounter.
The hosts looked to go in front minutes from the restart when Mpho Mvelase struck the top of the crossbar.
But they were handed a blow late on when Siyanda Xulu sneaked in at the near post for an advancing header past Nhlapo to put the Team of Choice in the last eight.
Eagles: Nyame, Mosebo, Brown, Manganyi, Cele, Kubeka (Nkewana 75’), Mvelase, Niang, Sauls (Ngubo 55’), Nene, Mncube (Zongo 50’).
Subs: Ndwandwe, Nkewana, Makgothi, Mashiane,Hlongwane, Ngubo, Zongo.
Maritzburg: Ofori, Sanoka, Fransman, Xulu, Thlone (Onyango 46’), Makaringe, Ndlovu (Kunene 90+7’), Shandu, Maboe, Mokate, Mekoa (De Reuck 90+6’).
Subs: Mpandle, Onyango, De Reuck, Mcdonald, Atouba, Twala, Kunene