Bulls bring back a Bok for Cheetahs
The Sharks, two points ahead of the Bulls on the standings, need to beat the Sunwolves on Friday to claim the Africa wildcard.
Defeat for the Sharks will leave the back door open for the Bulls to sneak into next week's quarterfinals next week.
Bulls coach Nollis Marais also recalled Tian Schoeman at flyhalf.
Van der Merwe will start at tighthead prop.
Both players started off the bench against the Sunwolves last weekend and swap places with Francois Brummer and Werner Kruger respectively.
There is one other change on the bench, with Bandise Maku coming in for Jaco Visagie.
Bulls captain Adriaan Strauss will on Saturday become the most capped South African hooker in the Super Rugby competition.
Strauss, playing in his 132 match, will surpass Bismarck du Plessis - who played 131 times as hooker.
He will also move into third spot for all time appearances behind Victor Matfield (148) and Jannie du Plessis (145).
Bulls: 15 Jesse Kriel, 14 Jamba Ulengo, 13 Dries Swanepoel, 12 Burger Odendaal, 11 Travis Ismaiel, 10 Tian Schoeman, 9 Piet van Zyl, 8 Renaldo Bothma, 7 Jannes Kirsten, 6 Pieter Labuschagne, 5 Marvin Orie, 4 Jason Jenkins, 3 Marcel van der Merwe, 2 Adriaan Strauss (captain), 1 Pierre Schoeman.
Replacements: 16 Bandise Maku, 17 Nqoba Mxoli, 18 Werner Kruger, 19 Grant Hattingh, 20 Arno Botha, 21 Rudy Paige, 22 Francois Brummer, 23 Sarel Marais.
Date: Saturday, July 15
Venue: Loftus Versfeld
Kick-off: 19.15 (17.15 GMT)
Referee: Craig Joubert (South Africa)
Assistant referees: AJ Jacobs (South Africa), Lourens van der Merwe (South Africa)
TMO: Johan Greeff (South Africa)