England Under-19s assumed a strong first-innings lead of 119 over their South Africa counterparts thanks largely to four wickets for Northamptonshire seamer Olly Stone.
Stone, who has made his senior Northants debuts in all three formats over the last two years, claimed 4-40 from 11 overs as the hosts were dismissed for 194 at Newlands.
Jonathan Tattersall and Dominic Sibley then played out nine overs without alarm to close day two of four on 24 without loss for a lead of 143.
Ed Barnard earlier added seven to his overnight 107 as the tourists improved on yesterday’s 277 for seven by 36.
Barnard and Miles Hammond continued in the circumspect manner they had ended yesterday but, after Hammond was fortunate to pick up two fours in a Vincent Moore over, Barnard lost his off stump to Michael Fassen.
Fassen had Gavin Griffiths lbw in his next over and Hammond was last out, flashing a catch behind off Moore on 39 from 124 balls.
Home opening batsmen Murray Coetzee and Andries Gous replied solidly until, immediately after sending a short ball for six, Gous was caught behind off Harry Finch.
Shaylin Pillay was surprised to be given caught down leg in Finch’s next over, but Coetzee and Diego Rosier responded with a boundary-laden stand of 50 that Hammond ended by trapping Rosier in front for 26.
Stone was introduced in the 39th over and soon struck twice in two balls, bowling Coetzee for 50 through the gate and having Vassilli Orros held at second slip.
David Bedingham offered some resistance only to top-edge Stone to mid-on. Three wickets fell in as many overs with Clyde Fortuin mis-timing Josh Shaw to midwicket and Fassen edging Stone behind.
That left the hosts 165 for eight and, when Lizaad Williams skied a slog-sweep to slip, Hammond had the last wicket given Craig Kirsten was yesterday ruled out of the game with a stress fracture of the lower back.