Cardiff - Ospreys wing Eli Walker will not make his debut for Wales against the Springboks on Saturday after pulling out with a hamstring injury.
The 21-year-old had been given his chance after injury ruled out Alex Cuthbert from the first of Wales's four November internationals.
But Walker sustained the injury in training on Thursday, and his place is now taken by Scarlets full-back Liam Williams, with Ospreys back Ashley Beck drafted in for a place on the bench.
"Eli pulled up this morning with a hamstring strain, we're not sure whether it's a grade one or two," said Wales assistant coach Rob Howley.
Walker will go for a scan, with Howley hinting he might be out for some time.
"It's a blow for us, he's come in in good form. I just feel so desperate and gutted for the player himself," the former Wales scrum-half said.
"He trained particularly well last week, been running on the wing for us.
"It's a shame for Eli but we have to make sure we focus on the weekend."
Saturday's match at the Millennium Stadium will be the first time the two countries have met since the Springboks edged a 2011 World Cup pool game in Wellington 17-16.
Wales, however, went on to reach the semi-finals and take successive Six Nations titles.
Yet the fact remains Wales have beaten the Boks just once in 26 internationals stretching back 107 years, back in 1999.
15 Leigh Halfpenny, 14 George
North, 13 Jonathan Davies, 12 Scott Williams, 11 Liam Williams, 10 Rhys
Priestland, 9 Mike Phillips, 8 Toby Faletau, 7 Sam Warburton (captain), 6
Dan Lydiate, 5 Alun Wyn Jones, 4 Bradley Davies, 3 Adam Jones, 2
Richard Hibbard, 1 Gethin Jenkins
Substitutes: 16 Ken Owens, 17
Paul James, 18 Scott Andrews, 19 Luke Charteris, 20 Justin Tipuric, 21
Lloyd Williams, 22 James Hook, 23 Ashley Beck
Patrick Lambie, 14 JP Pietersen, 13 Jaque Fourie, 12 Jean de Villiers
(captain), 11 Bryan Habana, 10 Morné Steyn, 9 Fourie du Preez, 8 Duane
Vermeulen, 7 Willem Alberts, 6 Francois Louw, 5 Flip van der Merwe, 4
Eben Etzebeth, 3 Frans Malherbe, 2 Bismarck du Plessis, 1 Tendai
Substitutes: 16 Adriaan Strauss, 17 Gurthrö Steenkamp
18 Coenie Oosthuizen, 19 Pieter-Steph du Toit, 20 Siya Kolisi, 21 Ruan
Pienaar, 22 JJ Engelbrecht, 23 Willie le Roux