Opener Mahmudul Hasan Joy has proved a big stumbling block for South Africa as he celebrated his first Test century to keep Bangladesh battling in the first Test in Durban.
After Saturday's afternoon session on the third day, Joy was still there on 106 not out, having hit 10 fours and a six.
His efforts enabled the visitors to reach 7-257 in their first innings to trail South Africa by 110 runs.
Mehidy Hasan Miraz was 24 not out after the pair came together on 6-216.
Mahmudul earlier helped Bangladesh recover to 5-183 at lunch, along with Litton Das (41). Their 82-run stand for the sixth wicket revived the tourists after they were in trouble on 5-101 in reply to South Africa's total of 367.
Litton was out soon almost immediately after lunch without adding to his score.
Nightwatchman Taskin Ahmed (1) lasted just two overs of the morning session before he was caught in the gully by Wiaan Mulder to give pace bowler Lizaad Williams a first Test wicket on his debut.
But that very early breakthrough was the only one for South Africa in the morning.
Bangladesh started the day on 4-98 after offspinner Simon Harmer took all four of those wickets for South Africa on the second day.