Wiaan Mulder and Maharaj then formed an 80-run partnership for the seventh wicket to take South Africa’s total near the 400-run mark.
Maharaj was the aggressor of the two, as he smashed four boundaries and three sixes to complete his fourth Test fifty in just 50 deliveries.
Taijul Islam finally ended the partnership by bowling out Mulder for 33.
But the session undoubtedly belonged to the Proteas as they took 106 runs off 25 overs to take further control over the contest.
The hosts earlier ended the opening day on 278-5 with Verreynne and Mulder unbeaten on 10 and 0 respectively.