Upfront, Jannie du Plessis and Sti Sithole start at tighthead and loosehead respectively, with Ruhan Straeuli packing down at the back of the scrum.
Viljoen moves to No 10 as a result of injuries to both Jordan Hendrikse and Eddie Fouche and Van Rooyen said it was not ideal for them to have those late disruptions.
"Losing both Jordan and Eddie is obviously a massive blow for us, meaning we had to make a few adjustments as we prepare for Saturday. It also provides a few guys in the squad with an opportunity to showcase their talent against quality opposition in the VURC," he concluded.
Kick-off is at 16h05 (SA time).
Emirates Lions: 15 Divan Rossouw, 14 Stean Pienaar, 13 Manuel Rass, 12 Burger Odendaal (captain), 11 Rabz Maxwane, 10 EW Viljoen, 9 Andre Warner, 8 Ruhan Straeuli, 7 Vincent Tshituka, 6 Jaco Kriel, 5 Pieter Janse van Vuren, 4 Ruben Schoeman, 3 Jannie du Plessis, 2 Jaco Visagie, 1 Sithembiso Sithole. Replacements: 16 Pieter Botha, 17 Morgan Naude, 18 Carlu Sadie, 19 Reinhard Nothnagel, 20 Sibusiso Sangweni, 21 Morne van den Berg, 22 Matt More, 23 Wandisile Simelane.