Shane Bond and Chris Martin shared seven wickets to put New Zealand in a strong position after the opening day of the first Test against South Africa.
Bond claimed 4-73 and new-ball partner Martin 3-67 as South Africa mustered only 226 all out at the Wanderers.
Opening batsman Herschelle Gibbs top scored with a restrained 63 but was given little support by his top-order colleagues.
New Zealand, who were being captained by Daniel Vettori for the first time in a Test, then reached 41-2 by stumps with both openers - Craig Cumming and Michael Papps - back in the pavilion.
Smith failed to justify his decision to bat first by playing onto his stumps for one in Martin's first over, and Hashim Amla (12) soon followed caught behind off Bond.
Gibbs and Jacques Kallis repaired the early damage to reach lunch at 73-2, although Kallis was dropped on two occasions.
Kallis (29), however, failed to make the most of his reprieves when he edged behind off Ian O'Brien from the first ball of the afternoon session. And Ashwell Prince (1) edged Bond to Stephen Fleming in the slips as the Proteas slumped to 92-4.
Gibbs and Abraham de Villiers shared a 49-run, fifth-wicket stand before Martin made his second intervention by having Gibbs caught by the sure-handed Fleming, who was back in the ranks after spending more than 10 years as captain.
De Villiers (33) and Mark Boucher (43) produced some brief resistance down the order, but Bond returned to add two more wickets as the hosts were all out for 226 during the evening session.
That left enough time for both Makhaya Ntini and Dale Steyn to pick up a wicket as New Zealand reached 41-2 in their reply, with Fleming striking three fours and a six to finish unbeaten on 22.
Ntini had Papps caught in the slips for two, while Steyn trapped Cumming lbw for 12.