Stormers scrumhalf on Scarlets bench
Jantjies has been signed on a short-term loan from the Stormers.
Scrumhalf Mike Phillips comes into the starting XV, as the only change to the backline, with Jonathan Evans sidelined with an ankle injury.
Openside flank James Davies makes a long-awaited return to action after recovering from shoulder surgery and comes straight back into the starting line-up, following the news that he has extended his stay in West Wales.
Will Boyde moves across the backline to No.8 with Josh Macleod moving to the replacements bench.
There is just one change in the Cheetahs team for the clash.
Craig Barry will be replacing Luther Obi on the right wing.
Obi broke his arm in the match against Edinburgh. Sibhale Maxwane will be providing cover on the bench and making his Cheetah and Pro14 debut when he sets foot to field.
Cheetahs: 15 Clayton Blommetjies, 14 Craig Barry, 13 William Small-Smith, 12 Nico Lee, 11 Makazola Mapimpi, 10 Fred Zeilinga, 9 Shaun Venter, 8 Junior Pokomela, 7 Rynier Bernardo, 6 Paul Schoeman, 5 Reniel Hugo, 4 Carl Wegner, 3 Johan Coetzee, 2 Torsten Van Jaarsveld (captain), 1 Charles Marais.
Replacements: 16 Jacques du Toit, 17 Retshegofaditswe Nche, 18 Tom Botha, 19 Jasper Wiese, 20 Daniel Maartens, 21 Tian Meyer, 22 Tertius Kruger, 23 Sibhale Maxwane.
Scarlets: 15 Johnny Mcnicholl, 14 Tom Prydie, 13 Steff Hughes (captain), 12 Paul Asquith, 11 Ioan Nicholas, 10 Dan Jones, 9 Mike Phillips, 8 Will Boyde, 7 James Davies, 6 Tadhg Beirne, 5 David Bulbring, 4 Lewis Rawlins, 3 Werner Kruger, 2 Ryan Elias, 1 Dylan Evans.
Replacements: 16 Taylor Davies, 17 Rhys Fawcett, 18 Simon Gardiner, 19 Steven Cummins, 20 Josh Macleod, 21 Herschel Jantjies, 23 Ioan Hughes, 23 Morgan Williams.
Date: Saturday, December 2
Venue: Free State Stadium, Bloemfontein
Kick-off: 19.30 (17.30 UK time; 17.30 GMT)
Referee: Quinton Immelman (South Africa)
Assistant referees: Stephen Geldenhuys (South Africa), Jaco Kotze (South Africa)
TMO: Marius Jonker (South Africa)