Leg-spinner Imran Tahir (four for 31) and Morne Morkel (three for 49) were the most successful of a frontline foursome completed by seamers Dale Steyn and Vernon Philander, as opener Daniel Bell-Drummond and then stoic number four Michael Powell stalled the tourists' progress at Canterbury.
There was time for 13 overs of batting, once Tahir had run through the tail, and for South Africa to close on 31 for the loss of captain Graeme Smith - caught behind to a thin and low edge to the wicketkeeper off Charlie Shreck.
Smith had earlier chosen to bowl first, and the tourists could muster just one wicket in 29 overs on a bright morning. Bell-Drummond and Sam Northeast, leading his county for the first time, comfortably dealt with the new-ball threat.
The pair, England Under-19s of current and recent vintage, demonstrated to their seniors how to handle Steyn, Philander and Morkel in an opening stand of 81.
It was not until after six bowling changes, involving Jacques Kallis as well for all five options in Smith's Test attack, that Northeast succumbed in Steyn's second spell. He edged to slip, and Bell-Drummond was unable to add to his 42 before nicking Morkel behind as the tall fast bowler got one to hold its line from the Nackington Road End in the first over after lunch.
There followed a 22-over middle session in which Kent's young team managed 42 runs for the loss of three wickets. Ben Harmison did not convince, eventually falling lbw to Philander, and Alex Blake was also trapped in front by Morkel.
Powell took his apparent sheet-anchor brief to extremes, in an unbeaten 48 from 137 balls, but after Sam Billings had edged a drive at JP Duminy, to be well-held at slip, Matt Coles took on Steyn and counted boundaries with a lofted off-drive, pull past midwicket and a steer over gully.
Coles' departure, aiming to follow a slog-swept four off Tahir with a finer paddle but managing only an edge to slip, left Powell to try to eke out something substantial with the tail. He escaped a low caught-and-bowled chance, from a Tahir full-toss, on 35 - and took his cue to up the ante with some late strokeplay to push Kent past 200.
But by then, Tahir was busy making short work of nine, 10 and 11 - to leave his batting colleagues almost an hour in which to begin South Africa's reply, one which was to lose its lynchpin in the 11th over.
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