Follow live updates as Wales and the Springboks clash in Cardiff.
Live test rugby updates: Wales v South Africa
Gareth Anscombe was retained at flyhalf and Liam Williams brought in for the injured Leigh Halfpenny at fullback as Wales seek a clean sweep of their end-of-year tests against South Africa on Saturday.
Williams for Halfpenny, who hasn't recovered from a concussion, is the only change Gatland made to the Wales 15 that beat Australia 9-6 two weeks ago.
Williams made his 50th test appearance and played on the wing in the easy win over Tonga last weekend, when Wales rested many of its front-liners ahead of the Springboks test.
Coach Warren Gatland resisted any temptation on Thursday to switch Anscombe to fullback against South Africa as Wales goes for a fourth win from four games in the November series for the first time ever, and a ninth straight victory. It would equal Wales' previous best run back in 1999.
"We have rewarded the team that faced Australia with another start this weekend," Gatland said.
Williams scored two tries at left wing in the 74-24 blowout against Tonga, and was entrusted with the No. 15 jersey by Gatland for the test against the rebuilding Springboks.
Wales starts as favorite having won the last three encounters, and four out of the last five, including in June when Wales triumphed in the United States in South Africa coach Rassie Erasmus' first test in charge.
Despite the impressive show by some backup Wales players against Tonga, Gatland opted for his tried and tested. He retained his first-choice combinations in the forward pack, at scrumhalf-flyhalf with Gareth Davies and Anscombe, and on the wings with Josh Adams and George North helping Williams in the back three.
"There were a lot of tough selection calls, but that is what we want," Gatland said.
"We want to end the campaign with a big performance against a very good South African side."
Halfpenny's injury does, however, remove Wales' first-choice goalkicker. Gatland had the option of bringing reliable kicker Dan Biggar into the team at 10 and dropping Anscombe to 15, where he has played before.
Halfpenny was concussed in a late tackle by Australia center Samu Kerevi, a hit that drew criticism as reckless from the Welsh camp but went unpunished by officials.