South Africa captain Graeme Smith and fellow opener Neil McKenzie denied England a wicket on the fourth morning of the first Test at Lord's here on Sunday but the tourists still had much work to do if they were to save this match.
The Proteas, following-on, were 67 without loss at lunch - still needing a further 279 runs to make England bat again.
However, left-hander Smith was 36 not out, with McKenzie unbeaten on 24.
The closest England came to taking a wicket in the session was when Smith, on 26, got a thin inside edge off spinner Monty Panesar.
But keeper Tim Ambrose had stood up too soon and the, admittedly difficult, chance bounced off his pads.
South Africa resumed on 13 without loss, a huge 333 runs behind England's commanding 593 for eight declared, built on Ian Bell's Test-best 199 and 152 from Kevin Pietersen in his first Test innings against the land of his birth.
The Proteas knew that if they batted as badly as they did while being dismissed for a first innings 247, with Ashwell Prince's 101 the only major contribution, the opening match of this four-Test series could end with more than a day to spare.
Smith, whose decision to field first had backfired spectacularly, was eight not out and McKenzie one not out.
Left-armer Panesar had taken four for 74 in the first innings but it was the quicks who'd made inroads at the top of the order.
However, there was a heartening moment for South Africa when, off Sunday's second ball, McKenzie cover-drove left-arm quick Ryan Sidebottom for four.
Smith, who in the corresponding match five years ago made 259, the highest individual score by an overseas batsman in a Lord's Test, then played an elegant late cut four off fast bowler Stuart Broad.
However, when Panesar came on, as happened on Saturday, he started to get turn out of the footmarks outside the left-hander's off-stump. This proved a problem for Smith, troubled by Panesar either side of his escape.
And the fact Sidebottom had been bowling over the wicket from the Pavilion End meant there was now rough outside right-hander McKenzie's off-stump when he faced Panesar, operating from the Nursery End, to contend with as well.
Runs all but dried up, with England reeling off five successive maidens but South Africa's openers held firm.