"He makes a massive difference to their side.
"Once he's in there, he controls the game, the tempo of the game and he'll add a lot to their group."
To see just how much du Preez offers the Boks, superstar lock Victor Matfield said fans only needed to scrawl through South Africa's record in 2010 without him.
After romping to the Tri-Nations title with five wins from six matches in 2009, including an unprecedented three straight against the All Blacks, the Springboks finished last with just one victory last year.
"We all saw last year that we missed him. He's a quality player," Matfield said.
"His decision-making is very important, so it will be nice to have him back."
Genia first went head-to-head with du Preez at Super Rugby level two years ago and the pair also clashed twice in tests in 2009.
"You've got to keep an extra eye on him because he's a very cunning type of player," Genia said.
"He's a bit like [All Blacks half] Piri Weepu; he's very skilful and always has a lot of tricks in the bag - his kicking game, his running game and his vision.
"And just for the fact that he always makes the right decision and just controls a game very, very well, he's world-class and he'll make a massive difference.
"He challenges the whole group because he's that good."
Although his individual match-up with du Preez looms as potentially decisive, Genia said the onus was on every Australian player to perform at Kings Park to ensure the Wallabies bounced straight back from last week's 30-14 loss to the All Blacks in Auckland.
"You always look forward to playing against the best, whether it's an individual or a side, and he's the best there is, I think," Genia said.
"It's exciting to come up against him but for me it's not too much about individuals. It's about [performing] collectively as a group."
Centre Adam Ashley-Cooper says the Wallabies are fortunate they don't have to wait long before getting the chance to atone for last week's Eden Park disappointment.
"That was the positive we were taking out of Auckland - the fact that we had seven days to turn it around," Ashley-Cooper said.
"Everyone's pretty excited by that - getting our Tri-Nations campaign back on track.
"It's just a good opportunity to get another great win and build momentum this week."
- AAP
