Lydiate returns for Wales
Lydiate's inclusion in the team is one of three changes to the team that lost 6-15 to Australia lst weekend.
Prop Jenthin Jenkins also comes back into the starting line-up to feature in his 18th World Cup match and he packs down alongside Scott Baldwin and Samson Lee.
Tyler Morgan's return to the team is the only change in the backline – he partners Jamie Roberts in midfield. Alex Cuthbert will make his 40th Wales appearance in a back three alongside George North and fullback Gareth Anscombe.
Luke Charteris and Alun Wyn Jones continue in the second row with the latter making his 100th international appearance [94th for Wales, plus six British and Irish Lions appearances].
"After coming through an incredibly tough pool, we are excited to be in the quarterfinals and returning to Twickenham," said Wales head coach Warren Gatland.
"The physicality and intensity of the matches so far will stand us in good stead for what is going to be a huge battle against the Springboks.
"They have grown game on game in this tournament and we know the challenge that faces us from a talented South African side."
Ken Owens, Paul James and Tomas Francis are named as the front-row replacements with Bradley Davies and Justin Tipuric completing the forward contingent. Lloyd Williams, Rhys Priestland and James Hook are named as the replacement backs.
Wales: 15 Gareth Anscombe, 14 Alex Cuthbert, 13 Tyler Morgan, 12 Jamie Roberts, 11 George North, 10 Dan Biggar, 9 Gareth Davies, 8 Taulupe Faletau, 7 Sam Warburton (captain), 6 Dan Lydiate, 5 Alun-Wyn Jones, 4 Luke Charteris, 3 Samson Lee, 2 Scott Baldwin, 1 Gethin Jenkins.
Replacements: 16 Ken Owens, 17 Paul James, 18 Tom Francis, 19 Bradley Davies, 20 Justin Tipuric, 21 Lloyd Williams, 22. Rhys Priestland, 23. James Hook.
Date: Saturday, October 17
Venue: Twickenham, London
Kick-off: 16.00 (15.00 GMT; 17.00 SA time)
Referee: Wayne Barnes
Assistant referees: George Clancy, JP Doyle
TMO: Graham Hughes
