The Cardiff Blues flanker, who has toured three times with the Lions, came on as a replacement for Wales in their recent 29-25 defeat by the world champions at the Millennium Stadium. It will be his fifth outing in the famous Baa-Baas jersey and his second for the club against the Boks.
He scored a try in a famous 22-5 triumph at Twickenham and will be hoping to pick up another win over a side he hopes to meet when Wales launch their World Cup campaign against the defending champions in Wellington next year.
Australian outside half Matt Giteau has been handed the honour of leading the barbarians in the MasterCard Trophy match and he will be hoping to make it a hat-trick of wins over his country's two major rivals after figuring in the Baa-baas line-ups that beat the Boks in 2007 and the All Blacks last December.
In keeping with Barbarian tradition, the starting XV includes two uncapped players - Stormers skipper Anton van Zyl and Chiefs No 8 Colin Bourke. Cardiff Blues and Wales prop John Yapp is included among the replacements.
Barbarians: James O'Connor (Australia); Joe Rokocoko (New Zealand), Adam Ashley-Cooper (Australia), Ma'a Nonu (New Zealand), Drew Mitchell (Australia); Matt Giteau (Australia, captain), Will Genia (Australia); Salvatore Perugini (Italy), Stephen Moore (Australia), Neemia Tialata (New Zealand), Anton van Zyl (Stormers), Chris Jack (New Zealand), Rodney So'oialo (New Zealand), Martyn Williams (Wales), Colin Bourke (Chiefs)
Replacements: Keven Mealamu (New Zealand), John Yapp (Wales), Quintin Geldenhuys (Italy), Daniel Braid (New Zealand), Andrew Ellis (New Zealand), Stephen Donald (New Zealand), Seru Rabini (Fiji)