The goal was scored by Tamsanqa Sangweni.
Spurs looked promising early on, showing good intent in attack and keeping their Premiership opponents on the back foot with a couple of shots from range.
But gradually AmaZulu began to break into their stride and around the 20 minute mark they succeeded in getting several attempts on goal.
The first came from Andile Khumalo, but he skewed his shot wide from 16-yards out.
Then Ayanda Dlamini had two efforts on goal in quick succession: the first struck a defender, and the second saw his goal-bound header cleared off the line.
But from that clearance in the 29th minute, Usuthu were to take the lead in scintillating fashion as Tamsanqa Sangweni struck with a wonder goal: from well over 30-yards out he sent a sizzling left-footed dipping volley into the back of the net.
The hosts had chances to extend their lead, but Dlamini headed over the bar from Moses Chavula’s pin-point cross, while Tangeni Shipahu sent an effort into the side-netting.
The visiting side had by no means been overwhelmed by AmaZulu in the first half, and started the second stanza in a positive vain.
But they could just not muster enough pressure in the Usuthu box to mount any serious threat of a come-back.
When chances came, Spurs were was wasteful, as Dumisane Gamede fired wide with the goal at his mercy in the 54th minute and again ten minutes later.
For the most part the KZN side were comfortable in the final 20 minutes of the game and could have more goals, but Spurs keeper Briace Msiza made a couple of superb saves to deny Goodman Dlamini and then Ayanda Dlamini.
AmaZulu: Kapini; Mokoro, Mayongo, Zhuwawo, Mbhele; Chavula (Zwane 73’), Sangweni, Khumalo, Shipahu; Lewis (G Dlamini 71’), A Dlamini (Vilane 93’)
Spurs: Msiza; Papa, Theba, Rooi, Zwane, Tshehla, Mbonani, Nzimande, Pa Mubayiwa (Gamede 40’) (Skoshana 70’); Pe Mubayiwa, Matema