The opening stages of the match was a scrappy affair, with neither side able to hold onto possession for too long.
The visitors opened the scoring in the 20th minute when Ngwenya found the back of the net with low shot following a quick counter-attack after the AmaZulu defence cleared a free-kick by Platinum Stars.
The hosts’ first real shot at goal arrived in the 32nd minute via the boot of Bekithemba Ndlovu, but his long range effort flew narrowly wide.
Stars threatened again in the 35th minute when skipper Stanley Kgatla sent a good cross into the area, but midfielder Wonder Nhleko sent his header just over the crossbar.
Nhleko went close to leveling the score two minutes before the break when his long range effort hit the crossbar, with Usuthu keeper Lawrence Ncala well-beaten.
The score remained 1-0 at half-time.
The second half was an extremely poor advertisement for South African football, with no real chances created by either side, and it was a stop-start affair, littered with silly fouls.
Both teams resorted to long range efforts, which never threatened the opposing goal, and both coaches will do well to drill their players, at least those not reporting for international duty, at training before their next fixture.