Kgotso Moleko, Thabo Qalinge and Luvuyo Memela came in from Usuthu's goalless draw with Swallows FC and Thembela Sikhakhane, Siyethemba Sithebe and Matarr Ceesay vacated.
A strong start from AmaZulu had Memela running in behind the defence from a through ball and a free-kick in a promising area by the same player and Sphesihle Maduna.
Big Bullets weren't overawed amidst Usuthu's pressure and snatched the lead following the opening half-hour mark after Chiukepo Msowoya pounced on a goalkeeping error by Veli Mothwa.
The joy turned inside minutes as a strong challenge near the danger area by Yamikani Fodya led to his marching orders and forced Big Bullets to finish the half with ten players.
Usuthu should've been level ahead of halftime after a flowing move down the right freed in Maduna, who hoofed Lehlohonolo Majoro's cutback over the top from close-range.
Big Bullets altered their stall minutes before the interval in the way of Precious Phiri for the goal-scorer and former Orlando Pirates striker Msowoya.
AmaZulu spurned another big chance two minutes after halftime with a header from close-range by substitute Siphelele Mthembu, but the lanky forward headed over the top.
The host kept piling on the pressure inside the final stages in the hope of getting a way back, but Memela and Philani Zulu's adventures led to absolute naught whilst having a goal disallowed.
Late drama had Usuthu's Keagan Buchanan striking the woodwork twice from two close-range attempts, while Tapelo Xoki spurned a free-kick, as Bullets stunned AmaZulu.
AmaZulu: Mothwa, Moleko, Xoki, Malepe, Zulu, Mlambo, Makhaula, Qalinge, Luvuyo, Majoro, Maduna.
Subs: Boshoff, Mgwazela, Mzava, Gumede, Masilela, Buchanan, Sithebe, Ekstein, Mthembu.