England stare down the barrel
Following the high of a 211-run victory at Lord's a week ago, this was a chastening day for England, who have to pull off a Test record run chase if they are to secure an unlikely victory.
The surface offered less assistance to the pace bowlers than the first two days, but the home side would not have been pleased to see examples of the ball keeping low late on.
Tactics were occasionally imaginative - the off side packed or leg-side catchers employed for the short ball - and the bowling wholehearted, even if paceman Mark Wood again looked innocuous in 18 wicketless overs.
But most of England's efforts were repelled by a South Africa side who demonstrated all the patience, discipline and application that eluded the hosts on day two.
Amla leads Proteas' plod
It was Amla (87) who epitomised South Africa's relentless accumulation, only bursting to life at the sight of Liam Dawson, hitting the left-arm spinner down the ground.
Still, it was Dawson who removed Amla, correctly reviewing a rejected lbw appeal after the right-hander advanced down the pitch.
Elgar (80) earlier shared a stand of 135 with Amla, but the left-hander showed no great fluency before he was bounced out by Stokes.
England chipped away, but the compact Du Plessis (63) was another to show restraint until he was trapped by a Stokes delivery that scuttled through.
Off-spinner Moeen benefited as the visitors accelerated towards a declaration, claiming his fourth wicket by holding a return catch from Vernon Philander (42), who had just hoisted two massive leg-side sixes from successive balls.
During this match, Hashim Amla has overtaken AB de Villiers to go third on South Africa's all-time Test run-scorers' list (8,157). He is behind Jacques Kallis (13,206) and Graeme Smith (9,253)
