Knox, 33, kicked three penalties and two conversions as Australia gained a convincing Tri-Nations series win, just a month after he left Australia to play provincial rugby in South Africa after being convinced his Test career was over.
Knox had been in outstanding form with Australian Capital Territory during the Super-12 series, but selectors ignored his credentials and gambled instead by switching the veteran centre, Tim Horan, to outside-half.
Knox applied and was granted permission by the Australian Rugby Union to accept a deal with Natal - under the proviso that he return to play for his country if needed.
The recall clause was put into action last week after Horan, whose performances in the No 10 jersey had been roundly criticised, fractured his hand in last weekend's defeat by New Zealand. Knox arrived just four days before the match, but slotted in easily and was one of Australia's best players in their win.
Knox's initial disappointment at missing selection for the Australian team had been countered in part by how much he had enjoyed playing with Natal. He has already pledged to return to South Africa this season, but his performance against some of his new team-mates on Saturday ensured he will retain his place in the Australian team for the forthcoming Tri- Nations Tests in New Zealand and South Africa.
"I was just happy to be back. I'm part of a team and I'm happy if I've played all right and the back line has gone well," he said.
Australia scored four tries to three, with the man of the match, Ben Tune, crossing for two, in the 19th and 40th minutes.
The No 8 Daniel Manu and the full-back Stephen Larkham collected Australia's other touchdowns, while the prop Os du Randt, the stand-off Jannie De Beer and the lock Mark Andrews scored for the Springboks.
Australia: Tries Larkham, Manu, Tune 2; Conversion Knox 3; Penalties Knox 2. South Africa: Tries Du Randt, Andrews, De Beer; Conversion De Beer; Penalty De Beer.
AUSTRALIA: S Larkham (ACT); B Tune (Queensland), J Little (Queensland), J Holbeck (ACT), J Roff (ACT); D Knox (ACT), G Gregan (ACT); R Harry (NSW), M Foley (Queensland), A Heath (NSW), O Finegan (ACT), J Eales (capt, Queensland), M Cockbain (NSW), D Wilson, D Manu (NSW). Replacements: T Coker (ACT) for Manu, 56; B Robinson (ACT) for Cockbain, 58; A Blades (NSW) for Heath, 71.
SOUTH AFRICA: R Bennett (Border); A Snyman (Northern Transvaal), P Montgomery (Western Province), D van Schalkwyk (Northern Transvaal), P Rossouw (Western Province); J de Beer (Free State), J van der Westhuizen (Northern Transvaal); O du Randt (Free State), N Drotske (Free State), D Theron (Griqualand West), K Otto (Northern Transvaal), M Andrews (Natal), R Kruger (Northern Transvaal), A Venter (Free State), G Teichmann (capt, Natal). Replacement: A Garvey (Natal) for du Randt, 61.
n The New Zealand provincial side, Auckland, have bought a share in Blackheath, with the intention of using the club to develop between six and 12 of their young players who have English grandparents.Reuse content