Moeen Ali was England's most successful bowler on the opening day of the fourth and final Test with South Africa in Centurion.
The Worcestershire all-rounder dismissed Dean Elgar and JP Duminy at opposite ends of the day.
He has now taken 10 wickets in the series.
Moeen finished with figures of 2-53 from 17 overs on a day of fluctuating fortunes for England who have already clinched the Basil D'Oliveira Trophy.
South Africa, who were 237-1 at one stage, eventually closed on 329-5 from 90 overs.
Moeen came into the attack in the 11th overand enjoyed immediate success in dismissing Elgar for 20 with 35 on the board.
Elgar skipped out of his crease and aimed an expansive shot down the ground but only managed an inside edge and James Taylor took another fine catch at short leg.
Moeen's second success accounted for Duminy (16) after he went for a big hit towards mid wicket and was trapped lbw with South Africa then 273-5.
Much of the day was dominated by opener and debutant Stephen Cook – son of former Somerset batsman Jimmy Cook – and Hasim Amla.
Cook scored 115 and Amla 109 and shared in a second wicket stand of 202 before four wickets fell for 36 runs.