A century from wicketkeeper Kyle Verreynne powered South Africa to 308 all out and a lead of 202 on Tuesday in the first Test against Bangladesh in Mirpur.
Verreynne was last man out in South Africa's first innings on day two after scoring eight fours and two sixes in his 114.
He put on 119 for the seventh wicket with Wiann Mulder, who made 54, in reply to Bangladesh's 106.
For Bangladesh, pace bowler Mehidy Hasan Miraz took two of the four wickets to fall on Tuesday and spinner Taijul Islam finished with 5-122.