Bangladesh left-arm quick Mustafizur Rahman took 4/37 on debut and just missed a hat-trick as South Africa were bowled out for 248 on the first day of the first Test on Tuesday.
leg spinner Jubair Hossain, with 3/53, also dented the progress of the Proteas, who slumped from 136/1.
Another big contributor was fast bowler Mohammad Shahid, who was wicketless but brought pressure by conceding only 34 runs in 17 overs.
Temba Bavuma top-scored for South Africa with 54 while Faf du Plessis made 48, and opener Dean Elgar 47. Bangladesh was 7-0 in two overs at stumps.
The 19-year-old Mustafizur has been a revelation since his senior debut in April. He took five wickets as Bangladesh rebounded from losing the first ODI against Proteas to winning the series for the first time last week.
Brief Scores SA: 248 (Bavuma 54, du Plessis 48, Elgar 47; Rahmar 4/37, Hossain 3/53) lead B’desh: 7/0 by 241 runs.