Captain Hashim Amla remained unbeaten after this third Test double century as South Africa moved closer to forcing a draw against England in the second test at Newlands on Monday.
Amla was 200 not out at lunch with Faf du Plessis (81) at the other end, guiding the hosts to 3-428.
The blooming 160-run partnership between them helped South Africa cut their deficit to 201 after England's swashbuckling first innings total of 6-(dec)629.
Dropped twice on Monday, an otherwise unflappable Amla betrayed nerves on 197, skying a shot and watching anxiously as Joe Root misjudged the ball and failed to get close to it.
Amla scrambled for two runs to go to 199 and brought up his double century off 461 balls in an innings that offers both him and South Africa much inspiration after 12 months of dismal test cricket.
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South Africa had kept England in the field through the entire third day on Monday, losing just one wicket and looked determined to inflict more energy-sapping misery on the visitors on the fourth day.
They started overnight on 3-353 and added 75 runs from 30 overs in the first session of the fourth day.
England produced some lively overs early on Tuesday but then turned to off spin as they moved closer to taking the third new ball, which is available immediately after lunch.
England did have a chance to catch du Plessis when he was on 61 but the edge flashed past James Anderson at first slip off the bowling of Moeen Ali.
It was similar to the catch that Anderson grassed on Monday when Amla got a thick edge to a delivery from Root.
England are 1-0 ahead in the four-test series.
