Alex Cuthbert, selected on the wing, and Johnny Williams, named at centre, make their first appearances this summer, as does Kieran Hardy who starts at scrum-half.
Teddy Williams and Cai Evans, named among the replacements for this fixture, are in line to win their first senior Wales caps on the weekend.
Jac Morgan, who starts at openside flanker, will captain the side for the second time. Dan Lydiate (blindside flanker) and Aaron Wainwright (No. 8) join Morgan in the Wales back row.
Elliot Dee (hooker) starts his first match this August, with Corey Domachowski (loosehead prop) and Keiron Assiratti (tighthead prop) winning their second caps and completing the Wales front row.
Ben Carter and Will Rowlands pair up in the second row. Dan Biggar (fly-half) is named in the starting XV after two appearances off the bench against England.
Mason Grady makes his first start this August, partnering Johnny Williams in the Wales midfield. Liam Williams is named at full-back for the second consecutive match. Rio Dyer completes the Wales starting line-up.
Among the replacements Tomos Williams and Max Llewellyn are alongside Evans as the back line cover.
Sam Parry, Nicky Smith and Henry Thomas are the Wales front row cover and Taine Basham, who was not a confirmed concussion following completion of all three stages of the head injury assessment (HIA) protocol*, provides the back row cover.
Gatland said: “Preparations have gone well. We’re really pleased with the whole squad. We’re trying to build some depth within the team and there’s been a great atmosphere.
“In the first couple of games what was really pleasing for me was the physicality we brought and the way we defended. There are still things for us to work on in terms of being much more accurate. There’s been a lot of learning from that second England game and hopefully we put that into practice against South Africa. There’s another opportunity for this group of 23 players to put their hand up before we select the world cup squad.
“We’re expecting confidence and physicality from South Africa. They don’t make a lot of mistakes. It’s a very experienced team for them. But we’ve got a great chance to go out there in front of a home crowd and produce some of the good things that we did in both the games against England. We just need to make sure we play for 80 minutes and are accurate for 80 minutes.”
Wales senior men’s XV to play South Africa at Principality Stadium in the 2023 Vodafone Summer Series
Saturday 19 August, KO 3.15pm BST. Live on Prime Video in English and welsh
15. Liam Williams (Kubota Spears – 85 caps)
14. Alex Cuthbert (Ospreys – 57 caps)
13. Mason Grady (Cardiff Rugby – 3 caps)
12. Johnny Williams (Scarlets – 5 caps)
11. Rio Dyer (Dragons – 8 caps)
10. Dan Biggar (Toulon – 109 caps)
9. Kieran Hardy (Scarlets – 17 caps)
1. Corey Domachowski ( Cardiff Rugby – 1 cap)
2. Elliot Dee (Dragons – 42 caps
3. Keiron Assiratti (Cardiff Rugby – 1 cap)
4. Ben Carter (Dragons – 10 caps)
5. Will Rowlands (Dragons – 24 caps)
6. Dan Lydiate (Dragons – 70 caps)
7. Jac Morgan (Ospreys / Gweilch – 10 caps) captain
8. Aaron Wainwright (Dragons – 38 caps)
16. Sam Parry (Ospreys – 6 caps)
17. Nicky Smith (Ospreys – 43 caps)
18. Henry Thomas (Montpellier – 1 cap)
19. Teddy Williams (Cardiff Rugby – uncapped / heb gap)
20. Taine Basham (Dragons – 12 caps)
21. Tomos Williams (Cardiff Rugby – 47 caps)
22. Max Llewellyn (Gloucester Rugby – 1 cap)
23. Cai Evans (Dragons – uncapped)
*for more information about the HIA protocol, CLICK HERE