In a hard-fought contest, Terrence Mandaza bagged a brace after Thapelo Selepe cancelled out Mario Booysen's opener for United in regulation time at Charles Mopeli Stadium.
The Team of Choice joined holders Kaizer Chiefs in the next round of the competition, with Amakhosi earlier beating last year's finalists SuperSport United 2-0 at Soccer City.
Warriors threatened early on through efforts from Maliele Pule, Muziwandile Khwela and ex-AmaZulu striker Josef Lekata.
But the visitors drew first blood in the 52nd minute, as defender Booysen nodded in a Bhongolwethu Jayiya delivery.
Warriors, though, hit back 20 minutes later when Selepe was allowed to stab home inside the area off a route-one ball.
However, Mandaza netted a quick-fire double in the 105th and 107th minute to save the blushes of Steve Komphela's Premiership outfit.
African Warriors: Magagula, Pule, Mokhethi, Lebahi, Khwela, Sithole, Pule, Marakane, Van Tonder, Selepe, Lakata.
Maritzburg United: Vries, Awal, Booysen, Evans, Cloete, Mkhize, Smeekes, Hartog, Jayiya, Isaacks, Lentjies.