Cook 67*, Root 31*
Rabada removes Hales & Compton
Compton lbw to one that kept low
SA: De Kock 129*; Stokes 4-86
England lead 2-0 in four-match series
Andrew Samson
BBC Test Match Special statistician
Image source, Reuters"Quinton de Kock's 104-ball hundred is the second fastest by a South Africa wicketkeeper. Denis Lindsay was quicker at the Wanderers in 1967 against Australia."
Image source, Getty ImagesDe Kock really turning it on now. The first three balls of Moeen Ali's over got for four, six, four - the maximum even taking out the cameraman at long-on as he tried to get out of the way. South Africa rattle past 450 and England look not far short of hopeless.
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Tom Audsley: England have bowled some absolute tripe this morning.
Duncan Wright: How many runs has Bairstow cost England now? batting contribution doesn't matter if you miss this many chances with the gloves.
My TV screen shows JP Duminy and Kyle Abbott looking quizzically at a laptop screen. Surely they're not beating themselves up about their dismissals still? No, a particularly tough wordsearch is my bet.
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Jay: De Kock should have walked up to Bairstow, shook his hand and said 'thank you'. Ditto with Cook. Then raise his bat and all that.
Anish Kaul: Great century from Quinton De Kock. England look very flat, he could go on and bat for a good while longer.
Andy West: What is the record for most maiden test tons in one series? Bairstow, Bevuma, de Kock, Cook. Has this been bettered?
Can't get a wicket? Have no-one else to turn to? Who do you call? Ben Stokes, of course. The Ginger One is back. Collar up. He means business.
Andrew Samson
BBC Test Match Special statistician
"In the last six Test matches in Centurion, South Africa have had three centurions in an innings on three occasions."
How many different ways are there to encourage your bowler? Jonny Bairstow has a few. "Come on, Mo." "Nice, Mo." "Good, Mo." Can't fault him for effort, I suppose, but it doesn't quite have the same conviction as a couple of hours ago Piedt has faced 93 for his 17 now.
Mark Boucher
Former South Africa wicketkeeper on BBC Test Match Special
"England just want to get off the field now. They have been in the field for 124 overs and the sun certainly does take it out of you up here."
Plan B (or is it Plan F?) for England: Broad round the wicket to Piedt. First slip, third slip, leg slip, short leg. Can you guess what's coming next? Yep, it's time for the short stuff. Piedt tickles a four off his hips fine of that leg slip. Head-in-hands time. Broad ends the over with a muted appeal for lbw as he pins Piedt on the crease with a rare full one. Going down leg.
Michael Vaughan
Ex-England captain on BBC Test Match Special
"You can see why England are so desperate. Moeen musn't have seen that inside edge."
No, there's an inside edge. England's fielders all missed that one. As you were.
Michael Vaughan
Ex-England captain on BBC Test Match Special
"That must have hit Piedt outside the line."
What's this? Moeen has a half-hearted lbw appeal against Piedt turned down, but England - somewhat belatedly - want another look...
Andrew Samson
BBC Test Match Special statistician
Image source, Getty Images"This is the second time since readmission that a South Africa wicketkeeper has made a Test hundred against England. Mark Boucher was the other back in 1999 as a nightwatchman."
Michael Vaughan
Ex-England captain on BBC Test Match Special
"A splendid innings, strokeplay of the highest order all around the ground. He managed to get boundaries at the right time."
Image source, Getty ImagesAnd there it is! He was never going to hang around. Moeen is punched for a single between point and cover and Quinton de Kock has his first Test hundred. A roar from the batsman, a point of the bat towards the dressing room. That's two maiden Test tons in one game after Stephen Cook yesterday.
Broad on the money, Piedt up to the task. He's got a tidy defence, the number 10. Another maiden means De Kock is on strike for the next over...
Michael Vaughan
Ex-England captain on BBC Test Match Special
"De Kock is having a fine time. He has a nice swing of the bat. A lot of left-handers are like that - it looks so easy."
De Kock wants a piece of this. He calls Piedt through for a single to short fine-leg to get on strike - then wallops Moeen over mid-wicket and drives back over the bowler's head to go to 99. Ten off the over and a maiden Test ton is within touching distance.