In addition, Mel Deane will play his first match for Connacht since moving to Sale Sharks in 2000, linking up in midfield with Aidan Wynne, one of the Ireland Under-20s' Grand Slam stars.
Two others players who have returned to Connacht, Johnny O'Connor and Mike McCarthy, will start on the bench.
With injury concerns over a number of players, prop Brian McGovern, a member of the extended squad, has been selected on the bench as cover.
Tuesday's match will be broadcast live on Setanta Sports Ireland and the Connacht branch have produced a special souvenir match programme for the fixture which totals 60 pages. Included in the programme are features on Connacht's previous games against national sides, South Africa's prospects for the World Cup, and a profile of Connacht skipper Andrew Farley.
Connacht's South African prop Brett Wilkinson is also profiled, while Connacht coaches Michael Bradley and Eric Elwood recall their half-back partnership in the Irish team which featured at the 1995 World Cup in South Africa. There are pen-pictures of the Connacht squad for the 2007/08 season, a tribute to referees and many more features. The programme will cost â0¬5 to purchase.
South Africa are the third of the Southern Hemisphere's 'big three' nations to play Connacht in Galway since New Zealand's first visit in 1974, and Andrew Farley is counting down the minutes to kick-off.
"A fixture like this only comes along once in a while, with a province or a club taking on a country, and that has been reflected in the interest in the game," Farley told the Galway Independent.
"It is obvious from meeting people around town and through the province that this is a special fixture and the players are looking forward to it. We're very excited about testing ourselves against one of the favourites to lift the Webb Ellis trophy.
"Ultimately, what matters is to us is what happens when the Magners League kicks off in September and later when the European Challenge Cup starts, but this game has given an extra buzz to the pre-season training."
Connacht have a long history of playing national teams - they have met Spain, Argentina, New Zealand, Romania, Fiji, Canada, Western Samoa, Australia, Morocco and the Irish national team, who took on the Sportsground residents as part of their preparations for the 1999 World Cup, over the past 34 years.
The westerners have posted victories over Spain (7-3 in 1973 and 31-19 in 1990), Western Samoa (25-18 in 1988), Fiji (27-5 in 1995) and Morocco (30-5 in 1998) during that time.
CONNACHT (v South Africa): Danny Riordan; Ofisa Treviranus, Mel Deane, Aidan Wynne, John Hearty; Tim Donnelly, Conor McPhillips; Brett Wilkinson, Adrian Flavin, Robbie Morris, David Gannon, Andrew Farley (capt), John Muldoon, Ray Ofisa, Colm Rigney.
Replacements: Joe Merrigan, Brian McGovern, Michael Swift, Mike McCarthy, Johnny O'Connor, Tom Tierney, Peter Durcan.