England's bowlers had no answer as Graeme Smith marked his 100th Test with his 25th hundred and he and fellow centurion Hashim Amla wrested control at The Oval.
Smith (131) and Amla (183no) batted through almost three sessions together to set a new highest second-wicket stand for South Africa against England.
Initially, they were sustaining the tourists' recovery. But by stumps on day three, after Jacques Kallis (82no) had also joined in, South Africa's 403 for two gave them massive power to add and put England under extreme pressure for the remainder of this first Investec Test.
Smith and Amla reprised what they had witnessed themselves from Alastair Cook and Jonathan Trott two days ago.
England's stone-wallers added a mere 170 in 58 overs after the loss of captain Andrew Strauss for a duck at the very start of this series.
But in reply to 385 and after opener Alviro Petersen had also made nought yesterday, South Africa's captain and number three put on 259 together against a home attack rendered toothless on a slow pitch and able to take only Smith's wicket all day.
Smith batted at a conspicuously uneven tempo, on the way to and beyond his seventh hundred against England and fifth in this country.
The slowest first 50 runs of his 10-year career came from 160 balls, but he then stepped on the accelerator to reach three figures from only 41 more deliveries when he cut Tim Bresnan for his 16th four just before lunch.
By the time his chanceless innings was done, Bresnan bowling him via inside edge and pad with the second new ball in late afternoon, he had been at the crease for more than six hours, kept out 272 balls and hit 20 fours.
England tried to strangle his scoring rate by bowling outside off stump to the left-hander, so adept off his legs.
But Smith passed the patience test, and it was not until he was past his half-century that he began to milk runs this morning off Graeme Swann.
On a surface expected to eventually favour spin if the sun stays out, England then hatched a plan to bowl to Smith's strength a little more and post two midwicket catchers to Stuart Broad. But he took the calculated risk, and clipped two more boundaries to take his sudden surge of fours to six from 14 balls. Amla's nine-hour tour de force was often more pleasing on the eye.
He reached his 15th hundred from 199 balls, having hit 13 fours, the pick of which were his seventh and eighth - memorable back-foot force past extra-cover off James Anderson and then a drive on the up in the same direction off Broad.
England surprisingly turned to Ravi Bopara, before Bresnan, and then switched Swann to the pavilion end - and there was even an over for Kevin Pietersen before the new ball was taken.
But nothing Strauss did even hinted at a breakthrough, until Bresnan at last did the trick.
No respite was forthcoming thereafter either, Swann getting through 33 wicketless overs as Kallis underlined South Africa's domination in another century stand with Amla.
There was the occasional moment of encouragement from the pitch for the off-spinner. But everything seemed to be happening just a little too slowly for him to be a threat to world-class batsmen, once set.
Save for a half-chance to slip late yesterday on 40, Amla's innings was without blemish - and Kallis' 50 appeared an inevitability throughout the 94 balls required.
It is hard to see how world number ones England could do anything better than end up trying to save the match, over the last two days.
There was perhaps some solace in Swann's struggles, suggesting South Africa leg-spinner Imran Tahir may also have to work hard.
Even so, for the first time on home soil since Trent Bridge last year, Strauss' team will trail significantly after the first innings.
Back then, Ian Bell's big hundred put them back in charge on the way to a landslide win over India. There is little time for that sort of outcome here, where the hosts will surely be grateful to grind out a draw to stay in position to defend their table-topping status in this short series.