In keeping with one of the main themes of this first Test at Kingsmead, Bangladesh once again showcased some real grit and application to escape the Proteas' tight leash.
Despite initially extending their dominance from the previous day, the South African attack struggled at times to impose itself on the visiting batters as they made 298 on Saturday's third day.
That meant the Proteas could only muster a lead of 69, which would've left them disappointed as it probably should've been meatier.
They reached 6 without loss before bad light ended play about an hour early.
Bangladesh's hero was their rookie opener Mahmudul Hasan Joy, whose 137 was highly significant on two fronts.
Not only is his patient, highly skilful 326-ball effort his maiden Test century, he also became the first Tiger to make triple figures in Tests against the Proteas.
Considered a prodigy at junior level, the 21-year-old unequivocally confirmed his status as one of Bangladesh's brightest prospects as he again mixed patience with some considered spurts of attacking shots to eclipse his previous highest score of 78, made in only his third innings when the Tigers memorably thrashed the New Zealanders by 8 wickets Down Under in January.
He found a succession of dedicated batting partners, notably Litton Das (41), who curbed his generally more adventurous intent and helped him add 82 for the sixth wicket.
South Africa also made life difficult for themselves by dropping chances offered by both batters.
Litton in particular should've been back in the change-room on 16 when he edged a routine catch to slip off Lizaad Williams, only to see Elgar spill it.
Mahmudul was given a life on 64 when he went forward to a Harmer delivery and got an inside edge, but short-leg Sarel Erwee was pivoting to his left, which preventing him from making the grab.
It was a chance, but a distinctly more difficult one.
Debutant Williams (3/54), however, was rewarded for some lively spells by having nightwatchman Taskin Ahmed caught at gully by Wiaan Mulder, who took the sharp opportunity on the second grab, and seemed to given the hosts momentum again after castling Litton with a cracker two balls after the lunch interval.
Mulder took the useful scalp of Mehidy Hasan Miraz after tea, granting Williams and Duanne Olivier (1/36) a window to wrap things up despite some lusty late hitting from their talisman at the top of the order.