Northamptonshire resumed on 120-5, chasing an improbable 501 to win and van der Merwe was dropped off Trevaskis by Rishi Patel at wide first slip, but Zaib soon worked Holland off his legs to bring up the 150 in the 53rd over.
He straight drove Holland for four before running a single off the next delivery to reach his 50, before bringing up the 50 partnership with van der Merwe in style by pulling Trevaskis over mid-wicket for six.
Van der Merwe also started to locate the boundary ropes, dispatching two short balls through the off-side in the first over of a fresh Josh Hull spell before driving Holland through the covers.
Zaib’s long summer of batting finally ended though when he drove loosely at one from Hull, Stephen Eskinazi taking the catch at gully.
Trevaskis had two lbw shouts turned down against van der Merwe as he went to sweep but the Northamptonshire youngster deposited him over deep mid-wicket when he served up a juicy full toss.
After lunch, van der Merwe drove Patel through mid-wicket to bring up Northamptonshire’s 250 and then pulled him for another four next ball.
George Bartlett hit a wide ball from Wright over the vacant gully position to the ropes before driving Ian Holland straight down the ground as the partnership gathered pace.
Van der Merwe had a couple of nervous moments during a testing spell from Wright, playing his final game before retirement, but drove Holland confidently through the covers, while Bartlett punched Holland off the backfoot through cover to bring up the 100 partnership off 160 balls.
In an eventful over from Logan van Beek, van der Merwe hooked for four before Bartlett ran a single to reach his half-century.
And van der Merwe reached three figures off the final ball of the over as he pulled to fine leg, becoming only the third man to score a century on first-class debut for Northamptonshire after Alastair Storie in 1985 and David Sales in 1996.
Bartlett fell for 50 to the very next ball though when he steered Hull straight to backward point, ending a seventh-wicket stand of 128, and Trevaskis soon trapped both George Scrimshaw and Ben Whitehouse lbw.
Finally, the left-arm spinner then had van der Merwe brilliantly caught by Budinger at short leg to allow the celebrations began.
Match report supplied by ECB Reporters’ Network, supported by Rothesay
