At stumps, the Warriors were 158 for five in their stuttering reply to the intimidating total of the hosts.
At 85 for six, Colin Ingram (59) and Simon Harmer (31) had compiled a 72-run unbeaten partnership as they restored some stability to the Warriors innings.
Van der Merwe (205 not out, 260 ball, 24×4, 3×6), resuming on his overnight score of 80, soon eclipsed his previous best first-class score of 87, as he moved to a hundred off 168 balls and the fiery former Proteas player celebrated in typically enthusiastic fashion.
Support came from wicketkeeper batsman Mangaliso Mosehle (67) who joined Van der Merwe just before the close of play on day one.
Together the pair put on 184 runs for the sixth wicket – a record for the Titans in the format – scoring at an aggressive 4.45 runs to the over.
Wicketless in the entire first session of the day, the Warriors finally made the breakthrough with the scalp of Mosehle after lunch, caught JJ Smuts, bowled Colin Ackermann with the score on 515 for six.
Titans captain Henry Davids decided to bat on, and let Van der Merwe have a dip at his 200.
And, Van der Merwe did so in emphatic fashion with a six over long-on when he was on 199 to bring up his memorable milestone off 260 balls.
It would prove to be the last ball of the innings, as the Titans declared with just over two-and-a-half days remaining.
In Potchefstroom, the Lions recovered from 20 for two overnight to a fighting 311 for seven at stumps against the Knights.
The Lions gained an 44-run lead on the Knights’ first innings of 267, courtesy of a Thami Tsolekile century on the second day.
Shortly before the close of play Tsolekile was run out for 113 by Quinton Friend. The breakthrough ended an 87 run partnership for the seventh between Hardus Viljoen and Tsolekile.
At stumps, Viljoen was 42 not out, with Aaron Phangiso (5) at the other end.
Dillon du Preez ended the day with figures of 3/35. Earlier, wicketkeeper-batsman, Quinton de Kock continued his good form starting out the season, with a third successive half-century in an 81-ball knock of 52.
The Proteas player was out caught behind by Rudi Second off the bowling Dillon du Preez as the Lions lost their fifth with the score on 138.