Maritzburg coach Eric Tinkler called on Nazeer Allie, Pogiso Sanoka and Yannick Zakri, while Usuthu brought Marc Van Heerden Tsepo Gumede, Sibusiso Mabiliso and Samuel Darpoh.
After a relatively quiet early start, Maritzburg nearly seized the opener when Thabiso Kutumela’s free-kick cannoned off the right-hand post on 20 minutes.
Eric Tinkler’s side received another opening when Zakri barked down the right side, but Siyabonga Mbatha rushed off the line to make a point-blank save.
Out of nowhere, Usuthu grabbed the lead when Bandile Shandu’s defensive clearance landed into his own net on the brink of halftime.
The Team of Choice squandered a good chance to get level shortly after the break when Shandu’s left-footed strike dragged wide of the net two minutes from the break, while Kutumela failed to beat Mbatha from six-yards out after the hour as Maritzburg's frustration grew.
Mbatha was finally beaten when Fortune Makaringe poked home from close-range after Usuthu failed to clear their lines.
As Usuthu looked for a way back, Maritzburg snatched the winning goal as Moseamedi volleyed home the winner a minute into time added on after being set up by Mohau Mokate.
Usuthu’s top eight chances suffer yet another knock with the defeat, while United’s survival prospects look all the more promising.
Maritzburg: Ofori, Kunene, Xulu, Allie, Sanoka, Makaringe, Timm, Kutumela, Ndlovu, Zakri, Shandu.
Subs: Mpandle, Figareido, Matsi, Mokate, Kateregga, Moseamedi, Mekoa.
AmaZulu: Mbatha, M.Gumede, Mabaliso, Van Heerden, T.Gumede, Darpoh, Morton, Vilakazi, Chawapihwa, Ncobeni, Ntuli.
Subs: Josephs, Ouro-Akoriko, Sikhakhane, Sithebe, Ncube, Karuru, Cele.