Van der Merwe’s batting has been a revelation for the Titans over the past year, which has seen him elevated to a middle-order role in which he has flourished.
The 29-year-old scored a career-best 87 after he was promoted to No. 4 in a Sunfoil Series clash against the Knights in March, and he bettered that by some distance on Friday as he hit an unbeaten 205 to lead the Titans to a first innings score of 539 for six declared.
Van der Merwe’s score was the highest by a Titans batsman against the Warriors, eclipsing the 203 that Heino Kuhn made in a fixture at Supersport Park during the 2008/09 season.
The Titans bowlers backed up their batsmen by reducing the Warriors to 45 for four, before Colin Ingram led a revival that saw the visitors go to stumps on 158 for five - still trailing by 381 runs.
Van der Merwe had begun the day on 80 with the Titans on 336 for five, and became more and more aggressive as the innings wore on.
He shared a 184-run stand with overnight partner Mangaliso Mosehle, who made 67, and then increased his scoring rate as the declaration grew closer.
A booming six brought up his double off just 265 balls and brought the declaration, before Juan de Villiers struck with his second ball and Farhaan Behardien took two wickets in his first two overs.
Ingram eventually found reliable support from Simon Harmer, and the pair put on an unbroken stand of 72 as the captain went to stumps on 59 while Harmer had 31.