Durban - An astonishing error from Golden Arrows goalkeeper Virgil Vries proved decisive as AmaZulu sealed a 2-1 victory in the Premiership derby in Umlazi, outside Durban, on Wednesday.
After a quiet first half, the visitors opened the scoring when Robyn Johannes' 56th minute back pass rolled under the legs of the Abafana Bes'thende custodian to stun the home crowd.
Bongani Mbele doubled the advantage with a crisp finish 18 minutes later, before Mzuvukile Tom pulled one back to set up a tense finish.
Usuthu sealed their third win in four league games to continue their resurgence under new coach Roger Palmgren, climbing to 10th in the table.
Muhsin Ertugral's Arrows slipped to a seventh loss in 10 league games this term.
Buoyed by their recent turnaround, AmaZulu looked far better early on as they knocked the ball around with plenty of assurance and endeavour.
They looked more organised too, though Arrows created the first real opening when Dillon Sheppard sent over a cross from the left that was not cleanly connected by Collins Mbesuma, allowing Tapuwa Kapini to gather easily.
Marc van Heerden tried to respond but curled his free kick straight at Vries.
Sheppard and Mbesuma combined once again just after the half-hour mark, with the Zambian sending his header over the crossbar.
Ramson Zhuwawo had a good chance to respond when he smartly turned and shot from inside the box, which Vries managed to parry, with his defenders booting the ball to safety.
Moments before the break, Thamsamqa Mkhize should have done better when Tom squeezed through a low cross from the left, and the midfielder hesitated as the chance went begging.
It was scoreless at the break and straight after the restart Musa Bilankulu should have put the hosts ahead with a free header from point blank range which was nodded into the stands.
Then came the goal which left Vries red in the face after he allowed the ball to roll in.
The home side tried to respond with another fine Mbesuma effort, but Usuthu remained patient and grabbed a second goal against the run of play when Tsweu Mokoro picked up a loose ball in his own half and sent a cross to Mbele, who controlled well and drilled the ball home from just inside the box.
Arrows halved the deficit in the 79th minute when Tom blasted home after collecting a ball over the top, though most of the AmaZulu defenders stopped moving in hope of an off-side decision that never came.