Hendrik Roodt was pencilled in among the starting XV, and if Van Heerden failed to recover in time, Mitchell said he would make his debut for the Lions in their clash with the Cheetahs at Coca-Cola Park on Saturday.
It was also unclear whether Jacobie Adriaanse or CJ van der Linde would play from the bench.
Hooker Callie Visagie and Tian Meyer were set to make their debuts for the Johannesburg-based franchise.
Stephan Greeff was also named in the match 22, playing his first game for the Lions off the bench.
Teams:
Lions: 15 Jaco Taute, 14 Deon van Rensburg, 13 Doppies le Grange, 12 Alwyn Hollenbach, 11 James Kamana, 10 Elton Jantjies, 9 Michael Bondesio, 8 Joshua Strauss (captain), 7 Derick Minnie, 6 Cobus Grobbelaar, 5 Franco van der Merwe, 4 Wikus van Heerden/ Hendrik Roodt, 3 Patric Cilliers, 2 Callie Visagie, 1 JC Janse van Rensburg.
Substitutes: 16 Martin Bezuidenhout, 17 Jacobie Adriaanse/ CJ van der Linde, 18 Hendrik Roodt / Stephan Greeff, 19 Warren Whiteley, 20 Tian Meyer, 21 Butch James, 22 Lionel Mapoe.
Cheetahs: 15 Hennie Daniller, 14 Dusty Noble, 13 Robert
Ebersohn, 12 Andries Strauss, 11 Rocco Jansen, 10 Johan Goosen, 9 Tewis
de Bruyn, 8 Davon Raubenheimer, 7 Lappies Labuschagné/Philip van der
Walt, 6 Heinrich Brüssow, 5 Izak van der Westhuizen, 4 Andries Ferreira,
3 WP Nel, 2 Adriaan Strauss (captain), 1 Trevor Nyakane
Substitutes:
16 Hercu Liebenberg, 17 Lourens Adriaanse, 18 Waltie Vermeulen, 19
Ashley Johnson, 20 Pieter van Zyl, 21 Sias Ebersohn, 22 Willie le Roux