This match between the two sides was billed as a grudge match after Maritzburg beat Chiefs 1-0 at the Orlando Stadium in the first round.
Chiefs started like a house on fire with their wide men, Abia Nale and Siphiwe Tshabalala attacking the United defence.
Against the run of play, the home side got their first chance to score in the 21st minute, when their striker Fadlu Davids hit a tame shot at Ithumuleng Khune.
The Chiefs goalkeeper showed signs of rustiness a minute later when he left his goal line to block Felix Obada's threathening run into his area but failed to stop the wingers' progress. As a result, Obada picked out Davids with a cross but the striker failed to keep his header on target.
The Amakhosi opened the scoring when Nale went on a surging run down the right flank and eventually squared a ball into the path of Nkosinathi Nhleko who side-footed past Shu-Aib Walters, making his debut in the Maritzburg goals.
The home team equaliser came from nowhere when Musa Nyatama ran straight through the middle of Chiefs defence to level matters two minutes before the interval.
With the heat taking its toll on the players, the tempo of the match decreased in the second half. Rudolph Bester hit the Chiefs crossbar with the a thunderous shot in the 63rd minute.
But it was Chiefs who went ahead when Jambo scored in the 82nd minute when he ran onto a well weighted pass from Jose Torrealba who came on as a substitute in these second half. The wingback fired home from a tight angle.
Nale put the contest beyond doubt when he ran past a static Maritzburg defence and stabbed the ball past Walters, two minute from the end.
At the press conference after the match, Middendorp conceded that his men lost concentration at the vital stage and this is what caused them to leve empty handed.