Oita - Wales suffered a late setback when centre Jonathan Davies was forced out of the side to play France in their Rugby World Cup quarter-final on Sunday with a knee injury, team officials said.
Kick-off is at 09:15 SA time.
The 31-year-old has aggravated a problem he sustained during the 29-17 Pool D win over Fiji earlier in the tournament, the Welsh Rugby Union announced shortly before kick-off.
Owen Watkin will take Davies' place at 13 with Leigh Halfpenny coming onto the bench for Wales, who start as favourites in Oita, southern Japan.
The winners of the clash will move on to face either South Africa or tournament hosts Japan in next week's semi-finals.
15 Liam Williams, 14 George North, 13 Owen Watkin, 12 Hadleigh Parkes, 11 Josh Adams, 10 Dan Biggar, 9 Gareth Davies, 8 Josh Navidi, 7 Justin Tipuric, 6 Aaron Wainwright, 5 Alun Wyn Jones (captain), 4 Jake Ball, 3 Tomas Francis, 2 Ken Owens, 1 Wyn Jones
Substitutes: 16 Elliot Dee, 17 Rhys Carre, 18 Dillon Lewis, 19 Adam Beard, 20 Ross Moriarty, 21 Tomos Williams, 22 Rhys Patchell, 23 Leigh Halfpenny
15 Maxime Medard, 14 Damian Penaud, 13 Virimi Vakatawa, 12 Gael Fickou, 11 Yoann Huget, 10 Romain Ntamack, 9 Antoine Dupont, 8 Gregory Alldritt, 7 Charles Ollivon, 6 Wenceslas Lauret, 5 Sebastien Vahaamahina, 4 Bernard Le Roux, 3 Rabah Slimani, 2 Guilhem Guirado (captain), 1 Jefferson Poirot
Substitutes: 16 Cyril Baille, 17 Camille Chat, 18 Emerick Setiano, 19 Paul Gabrillagues, 20 Louis Picamoles, 21 Baptiste Serin, 22 Camille Lopez, 23 Vincent Rattez