Full-back Leigh Halfpenny will turn out in a backline that includes Lions comrades George North, Jonathan Davies and Mike Phillips for the game against the Springboks.
And Lions skipper Sam Warburton will lead a forward pack dominated by Lions, including Toby Faletau, Dan Lydiate, Alun Wyn Jones, Adam Jones, Richard Hibbard and Gethin Jenkins, who withdrew before the tour but featured in 2009 and 2005.
Fellow Lion Justin Tipuric has been forced to settle for as place on the bench for the game, which kicks off Wales' autumn international series.
"We always say we like to test ourselves against the best and Saturday is going to be just that with a huge game against South Africa first up," said Gatland.
"The Springboks arrive in the UK off the back of their impressive Rugby Championship campaign and we know that we need to start well on Saturday.
"We go into the series as Six Nations Champions but we are looking forward to testing ourselves against the southern hemisphere sides and showing what we are can do."