Former Junior Springbok Van der Merwe takes the place of Seabelo Senatla, who has not recovered from a concussion sustained in last weekend’s 41-22 loss to the Lions.
Flanker Chris Massyn and lock David Meihuizen could also make their first appearances off the bench, the latter gaining an opportunity as Eben Etzebeth sits out with a broken hand.
Dillyn Leyds shifts to fullback in place of the injured Damian Willemse and Craig Barry takes his place on the right wing.
Hooker Bongi Mbonambi returns from injury to start alongside props Steven Kitshoff and Frans Malherbe in an all-Springbok front row, while Dan Kriel is at inside centre for Damian de Allende who is rested.
The Stormers are bottom of the South African Conference, but are still in with a chance of making the playoffs if they win their final two games of the regular season – home to the Sunwolves and Sharks.
(Reporting by Nick Said, editing by Ed Osmond)
